diff --git a/src/components/Dialog/ImportSongProjectDialog.vue b/src/components/Dialog/ImportSongProjectDialog.vue
index a4d2eadd57..a52bee0cfa 100644
--- a/src/components/Dialog/ImportSongProjectDialog.vue
+++ b/src/components/Dialog/ImportSongProjectDialog.vue
@@ -40,10 +40,17 @@
           >
             <QItemSection avatar>
               <QCheckbox
+                v-if="multiTrackEnabled"
                 v-model="selectedTrackIndexes"
                 :val="track.value"
                 :disable="track.disable"
               />
+              <QRadio
+                v-else
+                v-model="selectedTrackIndex"
+                :val="track.value"
+                :disable="track.disable"
+              />
             </QItemSection>
             <QItemSection>
               <QItemLabel>
@@ -110,6 +117,10 @@ const { dialogRef, onDialogOK, onDialogCancel } = useDialogPluginComponent();
 const store = useStore();
 const log = createLogger("ImportExternalProjectDialog");
 
+const multiTrackEnabled = computed(
+  () => store.state.experimentalSetting.enableMultiTrack,
+);
+
 // 受け入れる拡張子
 const acceptExtensions = computed(
   () => supportedExtensions.map((ext) => `.${ext}`).join(",") + ",.vvproj",
@@ -232,6 +243,23 @@ const trackOptions = computed(() => {
 });
 // 選択中のトラック
 const selectedTrackIndexes = ref<number[] | null>(null);
+const selectedTrackIndex = computed<number | null>({
+  get: () => {
+    if (selectedTrackIndexes.value == null) {
+      return null;
+    }
+    if (selectedTrackIndexes.value.length === 0) {
+      return null;
+    }
+    return selectedTrackIndexes.value[0];
+  },
+  set: (index: number | null) => {
+    if (index == null) {
+      throw new Error("assert: index != null");
+    }
+    selectedTrackIndexes.value = [index];
+  },
+});
 
 // データ初期化
 const initializeValues = () => {
diff --git a/src/components/Dialog/SettingDialog/SettingDialog.vue b/src/components/Dialog/SettingDialog/SettingDialog.vue
index 4b1677c0a4..d74ef2b31b 100644
--- a/src/components/Dialog/SettingDialog/SettingDialog.vue
+++ b/src/components/Dialog/SettingDialog/SettingDialog.vue
@@ -230,6 +230,7 @@
                 </QBtn>
               </QCardActions>
               <BaseCell
+                v-if="experimentalSetting.enableMultiTrack"
                 title="ソング：元に戻す対象のトラックの設定"
                 description="トラックの設定のうち、「元に戻す」機能の対象にする設定を指定します。"
               >
@@ -524,6 +525,17 @@
                   )
                 "
               />
+              <ToggleCell
+                title="ソング：マルチトラック機能"
+                description="ONの場合、１つのプロジェクト内に複数のトラックを作成できるようにします。"
+                :modelValue="experimentalSetting.enableMultiTrack"
+                :disable="!canToggleMultiTrack"
+                @update:modelValue="setMultiTrack($event)"
+              >
+                <QTooltip v-if="!canToggleMultiTrack" :delay="500">
+                  現在のプロジェクトに複数のトラックが存在するため、無効化できません。
+                </QTooltip>
+              </ToggleCell>
             </QCard>
             <QCard flat class="setting-card">
               <QCardActions>
@@ -896,6 +908,23 @@ const selectedEngineId = computed({
 const renderEngineNameLabel = (engineId: EngineId) => {
   return engineInfos.value[engineId].name;
 };
+
+// トラックが複数あるときはマルチトラック機能を無効化できないようにする
+const canToggleMultiTrack = computed(() => {
+  if (!experimentalSetting.value.enableMultiTrack) {
+    return true;
+  }
+
+  return store.state.tracks.size <= 1;
+});
+
+const setMultiTrack = (enableMultiTrack: boolean) => {
+  changeExperimentalSetting("enableMultiTrack", enableMultiTrack);
+  // 無効化するときはUndo/Redoをクリアする
+  if (!enableMultiTrack) {
+    store.dispatch("CLEAR_UNDO_HISTORY");
+  }
+};
 </script>
 
 <style scoped lang="scss">
diff --git a/src/components/Dialog/SettingDialog/ToggleCell.vue b/src/components/Dialog/SettingDialog/ToggleCell.vue
index 2b8ef85850..5245f7a34f 100644
--- a/src/components/Dialog/SettingDialog/ToggleCell.vue
+++ b/src/components/Dialog/SettingDialog/ToggleCell.vue
@@ -2,7 +2,11 @@
 
 <template>
   <BaseCell :title :description>
-    <QToggle :modelValue @update:modelValue="props['onUpdate:modelValue']">
+    <QToggle
+      :modelValue
+      :disable
+      @update:modelValue="props['onUpdate:modelValue']"
+    >
       <slot />
     </QToggle>
   </BaseCell>
@@ -16,6 +20,7 @@ const props = defineProps<
     modelValue: boolean;
     // eslint-disable-next-line vue/prop-name-casing
     "onUpdate:modelValue"?: (value: boolean) => void;
+    disable?: boolean;
   }
 >();
 </script>
diff --git a/src/components/Sing/ScoreSequencer.vue b/src/components/Sing/ScoreSequencer.vue
index 5a63fc3b61..ab19ff94ac 100644
--- a/src/components/Sing/ScoreSequencer.vue
+++ b/src/components/Sing/ScoreSequencer.vue
@@ -102,10 +102,21 @@
         }"
       ></div>
       <SequencerPhraseIndicator
-        v-for="phraseInfo in phraseInfos"
+        v-for="phraseInfo in phraseInfosInOtherTracks"
         :key="phraseInfo.key"
         :phraseKey="phraseInfo.key"
-        :isInSelectedTrack="phraseInfo.trackId === selectedTrackId"
+        :isInSelectedTrack="false"
+        class="sequencer-phrase-indicator"
+        :style="{
+          width: `${phraseInfo.width}px`,
+          transform: `translateX(${phraseInfo.x - scrollX}px)`,
+        }"
+      />
+      <SequencerPhraseIndicator
+        v-for="phraseInfo in phraseInfosInSelectedTrack"
+        :key="phraseInfo.key"
+        :phraseKey="phraseInfo.key"
+        isInSelectedTrack
         class="sequencer-phrase-indicator"
         :style="{
           width: `${phraseInfo.width}px`,
@@ -204,7 +215,6 @@ import {
 import { applyGaussianFilter, linearInterpolation } from "@/sing/utility";
 import { useLyricInput } from "@/composables/useLyricInput";
 import { ExhaustiveError } from "@/type/utility";
-import { getOrThrow } from "@/helpers/mapHelper";
 
 type PreviewMode =
   | "ADD_NOTE"
@@ -236,7 +246,7 @@ const notesInOtherTracks = computed(() =>
   ),
 );
 const overlappingNoteIdsInSelectedTrack = computed(() =>
-  getOrThrow(store.state.overlappingNoteIds, selectedTrackId.value),
+  store.getters.OVERLAPPING_NOTE_IDS(selectedTrackId.value),
 );
 const selectedNotes = computed(() =>
   store.getters.SELECTED_TRACK.notes.filter((note) =>
@@ -336,6 +346,16 @@ const phraseInfos = computed(() => {
     return { key, x: startX, width: endX - startX, trackId };
   });
 });
+const phraseInfosInSelectedTrack = computed(() => {
+  return phraseInfos.value.filter(
+    (info) => info.trackId === selectedTrackId.value,
+  );
+});
+const phraseInfosInOtherTracks = computed(() => {
+  return phraseInfos.value.filter(
+    (info) => info.trackId !== selectedTrackId.value,
+  );
+});
 
 const ctrlKey = useCommandOrControlKey();
 const editTarget = computed(() => state.sequencerEditTarget);
@@ -1408,7 +1428,9 @@ registerHotkeyWithCleanup({
     if (nowPreviewing.value) {
       return;
     }
-    store.dispatch("SELECT_ALL_NOTES_IN_SELECTED_TRACK");
+    store.dispatch("SELECT_ALL_NOTES_IN_TRACK", {
+      trackId: selectedTrackId.value,
+    });
   },
 });
 
@@ -1451,7 +1473,9 @@ const contextMenuData = computed<ContextMenuItemData[]>(() => {
       label: "すべて選択",
       onClick: async () => {
         contextMenu.value?.hide();
-        await store.dispatch("SELECT_ALL_NOTES_IN_SELECTED_TRACK");
+        await store.dispatch("SELECT_ALL_NOTES_IN_TRACK", {
+          trackId: selectedTrackId.value,
+        });
       },
       disableWhenUiLocked: true,
     },
diff --git a/src/components/Sing/SequencerPitch.vue b/src/components/Sing/SequencerPitch.vue
index 037d99e500..e03c86fd0e 100644
--- a/src/components/Sing/SequencerPitch.vue
+++ b/src/components/Sing/SequencerPitch.vue
@@ -54,7 +54,7 @@ const pitchEditData = computed(() => {
   return store.getters.SELECTED_TRACK.pitchEditData;
 });
 const previewPitchEdit = computed(() => props.previewPitchEdit);
-const selectedTrackId = computed(() => store.state.selectedTrackId);
+const selectedTrackId = computed(() => store.getters.SELECTED_TRACK_ID);
 const editFrameRate = computed(() => store.state.editFrameRate);
 const singingGuidesInSelectedTrack = computed(() => {
   const singingGuides = [];
diff --git a/src/components/Sing/SideBar/TrackItem.vue b/src/components/Sing/SideBar/TrackItem.vue
index ad8600f723..a893683268 100644
--- a/src/components/Sing/SideBar/TrackItem.vue
+++ b/src/components/Sing/SideBar/TrackItem.vue
@@ -158,7 +158,6 @@ import { useStore } from "@/store";
 import ContextMenu from "@/components/Menu/ContextMenu.vue";
 import { shouldPlayTracks } from "@/sing/domain";
 import { CharacterInfo, StyleInfo, TrackId } from "@/type/preload";
-import { getOrThrow } from "@/helpers/mapHelper";
 
 const props = defineProps<{
   trackId: TrackId;
@@ -179,7 +178,7 @@ const isThereSoloTrack = computed(() =>
   [...tracks.value.values()].some((track) => track.solo),
 );
 const shouldPlayTrack = computed(() =>
-  getOrThrow(shouldPlayTracks(store.state.tracks), props.trackId),
+  shouldPlayTracks(store.state.tracks).has(props.trackId),
 );
 
 const setTrackPan = (pan: number) => {
diff --git a/src/components/Sing/SingEditor.vue b/src/components/Sing/SingEditor.vue
index ecf72bd1da..354aed8b0a 100644
--- a/src/components/Sing/SingEditor.vue
+++ b/src/components/Sing/SingEditor.vue
@@ -62,7 +62,11 @@ const props = defineProps<{
 
 const store = useStore();
 
-const isSidebarOpen = computed(() => store.state.isSongSidebarOpen);
+const isSidebarOpen = computed(
+  () =>
+    store.state.experimentalSetting.enableMultiTrack &&
+    store.state.isSongSidebarOpen,
+);
 const sidebarWidth = ref(300);
 
 const setSidebarWidth = (width: number) => {
diff --git a/src/components/Sing/ToolBar/ToolBar.vue b/src/components/Sing/ToolBar/ToolBar.vue
index 18a3fc8036..1f8a50dea6 100644
--- a/src/components/Sing/ToolBar/ToolBar.vue
+++ b/src/components/Sing/ToolBar/ToolBar.vue
@@ -3,6 +3,7 @@
     <!-- configs for entire song -->
     <div class="sing-configs">
       <QBtn
+        v-if="multiTrackEnabled"
         class="q-mx-xs"
         :icon="isSidebarOpen ? 'menu_open' : 'menu'"
         round
@@ -168,6 +169,10 @@ const editor = "song";
 const canUndo = computed(() => store.getters.CAN_UNDO(editor));
 const canRedo = computed(() => store.getters.CAN_REDO(editor));
 
+const multiTrackEnabled = computed(
+  () => store.state.experimentalSetting.enableMultiTrack,
+);
+
 const { registerHotkeyWithCleanup } = useHotkeyManager();
 registerHotkeyWithCleanup({
   editor,
diff --git a/src/components/Sing/menuBarData.ts b/src/components/Sing/menuBarData.ts
index 6103917877..962afdf9aa 100644
--- a/src/components/Sing/menuBarData.ts
+++ b/src/components/Sing/menuBarData.ts
@@ -78,7 +78,9 @@ export const useMenuBarData = () => {
       label: "すべて選択",
       onClick: () => {
         if (uiLocked.value) return;
-        store.dispatch("SELECT_ALL_NOTES_IN_SELECTED_TRACK");
+        store.dispatch("SELECT_ALL_NOTES_IN_TRACK", {
+          trackId: store.getters.SELECTED_TRACK_ID,
+        });
       },
       disableWhenUiLocked: true,
     },
diff --git a/src/main.ts b/src/main.ts
index 400f4e347d..838b961b58 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -2,7 +2,7 @@ import { createApp } from "vue";
 import { createGtm } from "@gtm-support/vue-gtm";
 import { Quasar, Dialog, Loading, Notify } from "quasar";
 import iconSet from "quasar/icon-set/material-icons";
-import { store, watchStoreStatePlugin, storeKey } from "./store";
+import { store, storeKey } from "./store";
 import { ipcMessageReceiver } from "./plugins/ipcMessageReceiverPlugin";
 import { hotkeyPlugin } from "./plugins/hotkeyPlugin";
 import App from "@/components/App.vue";
@@ -18,7 +18,6 @@ window.dataLayer = [];
 
 createApp(App)
   .use(store, storeKey)
-  .use(watchStoreStatePlugin, { store })
   .use(
     createGtm({
       id: import.meta.env.VITE_GTM_CONTAINER_ID ?? "GTM-DUMMY",
diff --git a/src/sing/domain.ts b/src/sing/domain.ts
index f7d6b44e6e..6d84530b73 100644
--- a/src/sing/domain.ts
+++ b/src/sing/domain.ts
@@ -231,8 +231,8 @@ export function getNumMeasures(
   maxTicks = Math.max(maxTicks, lastTsPosition);
   maxTicks = Math.max(maxTicks, lastTempoPosition);
   if (notes.length > 0) {
-    const lastNote = notes[notes.length - 1];
-    const lastNoteEndPosition = lastNote.position + lastNote.duration;
+    const noteEndPositions = notes.map((note) => note.position + note.duration);
+    const lastNoteEndPosition = Math.max(...noteEndPositions);
     maxTicks = Math.max(maxTicks, lastNoteEndPosition);
   }
   return tickToMeasureNumber(maxTicks, timeSignatures, tpqn);
@@ -573,14 +573,11 @@ export const splitLyricsByMoras = (
  * ソロのトラックが存在する場合は、ソロのトラックのみ再生する。（ミュートは無視される）
  * ソロのトラックが存在しない場合は、ミュートされていないトラックを再生する。
  */
-export const shouldPlayTracks = (
-  tracks: Map<TrackId, Track>,
-): Map<TrackId, boolean> => {
+export const shouldPlayTracks = (tracks: Map<TrackId, Track>): Set<TrackId> => {
   const soloTrackExists = [...tracks.values()].some((track) => track.solo);
-  const shouldPlayMap = new Map<TrackId, boolean>();
-  for (const [trackKey, track] of tracks) {
-    shouldPlayMap.set(trackKey, soloTrackExists ? track.solo : !track.mute);
-  }
-
-  return shouldPlayMap;
+  return new Set(
+    [...tracks.entries()]
+      .filter(([, track]) => (soloTrackExists ? track.solo : !track.mute))
+      .map(([trackId]) => trackId),
+  );
 };
diff --git a/src/store/index.ts b/src/store/index.ts
index 0f63122ba7..ebf6bef826 100644
--- a/src/store/index.ts
+++ b/src/store/index.ts
@@ -1,4 +1,4 @@
-import { InjectionKey, Plugin } from "vue";
+import { InjectionKey } from "vue";
 import { createStore, Store, useStore as baseUseStore } from "./vuex";
 
 import {
@@ -23,7 +23,6 @@ import {
   singingStore,
   singingCommandStoreState,
   singingCommandStore,
-  singingStorePlugin,
 } from "./singing";
 import { projectStoreState, projectStore } from "./project";
 import { uiStoreState, uiStore } from "./ui";
@@ -413,16 +412,6 @@ export const store = createStore<State, AllGetters, AllActions, AllMutations>({
   strict: !isProduction,
 });
 
-// Storeをwatchするためのプラグインをまとめたもの。
-export const watchStoreStatePlugin: Plugin = {
-  install(
-    app,
-    { store }: { store: Store<State, AllGetters, AllActions, AllMutations> },
-  ) {
-    singingStorePlugin(store);
-  },
-};
-
 export const useStore = (): Store<
   State,
   AllGetters,
diff --git a/src/store/project.ts b/src/store/project.ts
index 630d4a54aa..7b3103e0df 100755
--- a/src/store/project.ts
+++ b/src/store/project.ts
@@ -134,8 +134,7 @@ export const projectStore = createPartialStore<ProjectStoreTypes>({
         await context.dispatch("CLEAR_PITCH_EDIT_DATA", { trackId });
 
         context.commit("SET_PROJECT_FILEPATH", { filePath: undefined });
-        context.commit("RESET_SAVED_LAST_COMMAND_IDS");
-        context.commit("CLEAR_COMMANDS");
+        context.dispatch("CLEAR_UNDO_HISTORY");
       },
     ),
   },
@@ -170,7 +169,7 @@ export const projectStore = createPartialStore<ProjectStoreTypes>({
      */
     action: createUILockAction(
       async (
-        { dispatch, commit, getters },
+        { dispatch, commit, state, getters },
         { filePath, confirm }: { filePath?: string; confirm?: boolean },
       ) => {
         if (!filePath) {
@@ -199,6 +198,20 @@ export const projectStore = createPartialStore<ProjectStoreTypes>({
             projectJson: text,
           });
 
+          if (
+            !state.experimentalSetting.enableMultiTrack &&
+            parsedProjectData.song.trackOrder.length > 1
+          ) {
+            await window.backend.showMessageDialog({
+              type: "error",
+              title: "エラー",
+              message:
+                "このプロジェクトはマルチトラック機能を使用して作成されていますが、現在の設定ではマルチトラック機能を使用できません。\n" +
+                "設定の「ソング：マルチトラック機能」を有効にしてからプロジェクトを読み込んでください。",
+            });
+            return false;
+          }
+
           if (confirm !== false && getters.IS_EDITED) {
             const result = await dispatch("SAVE_OR_DISCARD_PROJECT_FILE", {
               additionalMessage:
@@ -213,8 +226,7 @@ export const projectStore = createPartialStore<ProjectStoreTypes>({
           await applySongProjectToStore(dispatch, parsedProjectData.song);
 
           commit("SET_PROJECT_FILEPATH", { filePath });
-          commit("RESET_SAVED_LAST_COMMAND_IDS");
-          commit("CLEAR_COMMANDS");
+          dispatch("CLEAR_UNDO_HISTORY");
           return true;
         } catch (err) {
           window.backend.logError(err);
@@ -401,4 +413,11 @@ export const projectStore = createPartialStore<ProjectStoreTypes>({
       state.savedLastCommandIds = { talk: null, song: null };
     },
   },
+
+  CLEAR_UNDO_HISTORY: {
+    action({ commit }) {
+      commit("RESET_SAVED_LAST_COMMAND_IDS");
+      commit("CLEAR_COMMANDS");
+    },
+  },
 });
diff --git a/src/store/setting.ts b/src/store/setting.ts
index 035c391d7f..5603aeb82b 100644
--- a/src/store/setting.ts
+++ b/src/store/setting.ts
@@ -49,6 +49,7 @@ export const settingStoreState: SettingStoreState = {
     enableMultiSelect: false,
     shouldKeepTuningOnTextChange: false,
     enablePitchEditInSongEditor: false,
+    enableMultiTrack: false,
   },
   splitTextWhenPaste: "PERIOD_AND_NEW_LINE",
   splitterPosition: {
diff --git a/src/store/singing.ts b/src/store/singing.ts
index a90dd38ebd..a70b093e1a 100644
--- a/src/store/singing.ts
+++ b/src/store/singing.ts
@@ -1,5 +1,5 @@
 import path from "path";
-import { toRaw, watchSyncEffect } from "vue";
+import { toRaw } from "vue";
 import { createPartialStore } from "./vuex";
 import { createUILockAction } from "./ui";
 import {
@@ -21,7 +21,6 @@ import {
   SequencerEditTarget,
   PhraseSourceHash,
   Track,
-  WatchStoreStatePlugin,
 } from "./type";
 import { DEFAULT_PROJECT_NAME, sanitizeFileName } from "./utility";
 import {
@@ -154,6 +153,7 @@ const offlineRenderTracks = async (
   sampleRate: number,
   renderDuration: number,
   withLimiter: boolean,
+  multiTrackEnabled: boolean,
   tracks: Map<TrackId, Track>,
   phrases: Map<PhraseSourceHash, Phrase>,
   singingGuides: Map<SingingGuideSourceHash, SingingGuide>,
@@ -172,9 +172,9 @@ const offlineRenderTracks = async (
   const shouldPlays = shouldPlayTracks(tracks);
   for (const [trackId, track] of tracks) {
     const channelStrip = new ChannelStrip(offlineAudioContext);
-    channelStrip.volume = track.gain;
-    channelStrip.pan = track.pan;
-    channelStrip.mute = !getOrThrow(shouldPlays, trackId);
+    channelStrip.volume = multiTrackEnabled ? track.gain : 1;
+    channelStrip.pan = multiTrackEnabled ? track.pan : 0;
+    channelStrip.mute = multiTrackEnabled ? !shouldPlays.has(trackId) : false;
 
     channelStrip.output.connect(mainChannelStrip.input);
     trackChannelStrips.set(trackId, channelStrip);
@@ -257,38 +257,6 @@ const singingVoiceCache = new Map<SingingVoiceSourceHash, SingingVoice>();
 
 const initialTrackId = TrackId(crypto.randomUUID());
 
-export const singingStorePlugin: WatchStoreStatePlugin = (store) => {
-  // tracksの変更とtrackChannelStripsを同期する。
-  // NOTE: immerの差分検知はChannelStripだと動かないので、tracksの変更を監視して同期する。
-  watchSyncEffect(async () => {
-    if (!audioContext || !mainChannelStrip) {
-      return;
-    }
-    const shouldPlays = shouldPlayTracks(store.state.tracks);
-    for (const [trackId, track] of store.state.tracks) {
-      if (!trackChannelStrips.has(trackId)) {
-        const channelStrip = new ChannelStrip(audioContext);
-        channelStrip.output.connect(mainChannelStrip.input);
-
-        trackChannelStrips.set(trackId, channelStrip);
-      }
-
-      const channelStrip = getOrThrow(trackChannelStrips, trackId);
-      channelStrip.volume = track.gain;
-      channelStrip.pan = track.pan;
-      channelStrip.mute = !getOrThrow(shouldPlays, trackId);
-    }
-    const channelStripTrackIds = [...trackChannelStrips.keys()];
-    for (const trackId of channelStripTrackIds) {
-      if (!store.state.tracks.has(trackId)) {
-        const channelStrip = getOrThrow(trackChannelStrips, trackId);
-        channelStrip.output.disconnect();
-        trackChannelStrips.delete(trackId);
-      }
-    }
-  });
-};
-
 /** トラックを取得する。見付からないときはフォールバックとして最初のトラックを返す。 */
 const getSelectedTrackWithFallback = (partialState: {
   tracks: Map<TrackId, Track>;
@@ -325,7 +293,6 @@ export const singingStoreState: SingingStoreState = {
   sequencerSnapType: 16,
   sequencerEditTarget: "NOTE",
   _selectedNoteIds: new Set(),
-  overlappingNoteIds: new Map([[initialTrackId, new Set()]]),
   nowPlaying: false,
   volume: 0,
   startRenderingRequested: false,
@@ -604,15 +571,19 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
     },
   },
 
+  OVERLAPPING_NOTE_IDS: {
+    getter: (state) => (trackId) => {
+      const notes = getOrThrow(state.tracks, trackId).notes;
+      return getOverlappingNoteIds(notes);
+    },
+  },
+
   SET_NOTES: {
     mutation(state, { notes, trackId }) {
-      state.overlappingNoteIds.clear();
       state.editingLyricNoteId = undefined;
       state._selectedNoteIds.clear();
       const selectedTrack = getOrThrow(state.tracks, trackId);
       selectedTrack.notes = notes;
-
-      state.overlappingNoteIds.set(trackId, getOverlappingNoteIds(notes));
     },
     async action({ commit, dispatch }, { notes, trackId }) {
       if (!isValidNotes(notes)) {
@@ -630,7 +601,6 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
       const newNotes = [...selectedTrack.notes, ...notes];
       newNotes.sort((a, b) => a.position - b.position);
       selectedTrack.notes = newNotes;
-      state.overlappingNoteIds.set(trackId, getOverlappingNoteIds(newNotes));
     },
   },
 
@@ -644,10 +614,6 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
       selectedTrack.notes = selectedTrack.notes
         .map((value) => notesMap.get(value.id) ?? value)
         .sort((a, b) => a.position - b.position);
-      state.overlappingNoteIds.set(
-        trackId,
-        getOverlappingNoteIds(selectedTrack.notes),
-      );
     },
   },
 
@@ -667,11 +633,6 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
       selectedTrack.notes = selectedTrack.notes.filter((value) => {
         return !noteIdsSet.has(value.id);
       });
-
-      state.overlappingNoteIds.set(
-        trackId,
-        getOverlappingNoteIds(selectedTrack.notes),
-      );
     },
   },
 
@@ -693,14 +654,12 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
     },
   },
 
-  SELECT_ALL_NOTES_IN_SELECTED_TRACK: {
-    mutation(state) {
-      const selectedTrack = getSelectedTrackWithFallback(state);
-      const allNoteIds = selectedTrack.notes.map((note) => note.id);
-      state._selectedNoteIds = new Set(allNoteIds);
-    },
-    async action({ commit }) {
-      commit("SELECT_ALL_NOTES_IN_SELECTED_TRACK");
+  SELECT_ALL_NOTES_IN_TRACK: {
+    async action({ state, commit }, { trackId }) {
+      const track = getOrThrow(state.tracks, trackId);
+      const noteIds = track.notes.map((note) => note.id);
+      commit("DESELECT_ALL_NOTES");
+      commit("SELECT_NOTES", { noteIds });
     },
   },
 
@@ -1089,7 +1048,6 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
     mutation(state, { trackId, track }) {
       state.tracks.set(trackId, track);
       state.trackOrder.push(trackId);
-      state.overlappingNoteIds.set(trackId, new Set());
     },
     action({ state, commit, dispatch }, { trackId, track }) {
       if (state.tracks.has(trackId)) {
@@ -1109,7 +1067,6 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
       state.tracks.delete(trackId);
       const trackIndex = state.trackOrder.indexOf(trackId);
       state.trackOrder = state.trackOrder.filter((value) => value !== trackId);
-      state.overlappingNoteIds.delete(trackId);
       if (state._selectedTrackId === trackId) {
         state._selectedTrackId =
           state.trackOrder[trackIndex === 0 ? 0 : trackIndex - 1];
@@ -1142,7 +1099,6 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
   SET_TRACK: {
     mutation(state, { trackId, track }) {
       state.tracks.set(trackId, track);
-      state.overlappingNoteIds.set(trackId, new Set());
     },
     async action({ state, commit, dispatch }, { trackId, track }) {
       if (!isValidTrack(track)) {
@@ -1153,29 +1109,8 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
       }
 
       commit("SET_TRACK", { trackId, track });
-      // 色々な処理を動かすため、二重にセットする
-      // TODO: もっとスマートな方法を考える
-      await dispatch("SET_SINGER", {
-        singer: track.singer,
-        trackId,
-      });
-      await dispatch("SET_KEY_RANGE_ADJUSTMENT", {
-        keyRangeAdjustment: track.keyRangeAdjustment,
-        trackId,
-      });
-      await dispatch("SET_VOLUME_RANGE_ADJUSTMENT", {
-        volumeRangeAdjustment: track.volumeRangeAdjustment,
-        trackId,
-      });
-      await dispatch("SET_NOTES", { notes: track.notes, trackId });
-      await dispatch("CLEAR_PITCH_EDIT_DATA", {
-        trackId,
-      }); // FIXME: SET_PITCH_EDIT_DATAがセッターになれば不要
-      await dispatch("SET_PITCH_EDIT_DATA", {
-        pitchArray: track.pitchEditData,
-        startFrame: 0,
-        trackId,
-      });
+
+      dispatch("RENDER");
     },
   },
 
@@ -1183,12 +1118,6 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
     mutation(state, { tracks }) {
       state.tracks = tracks;
       state.trackOrder = Array.from(tracks.keys());
-      state.overlappingNoteIds = new Map(
-        [...tracks.keys()].map((trackId) => [trackId, new Set()]),
-      );
-      state.overlappingNoteInfos = new Map(
-        [...tracks.keys()].map((trackId) => [trackId, new Map()]),
-      );
       state._selectedTrackId = state.trackOrder[0];
     },
     async action({ commit, dispatch }, { tracks }) {
@@ -1197,11 +1126,7 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
       }
       commit("SET_TRACKS", { tracks });
 
-      for (const [trackId, track] of tracks) {
-        // 色々な処理を動かすため、二重にセットする
-        // TODO: もっとスマートな方法を考える
-        await dispatch("SET_TRACK", { trackId, track });
-      }
+      dispatch("RENDER");
     },
   },
 
@@ -1548,21 +1473,47 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
         const transportRef = transport;
 
         // レンダリング中に変更される可能性のあるデータをコピーする
-        const tracks = structuredClone(toRaw(state.tracks));
-        const trackChannelStripsRef = new Map(trackChannelStrips);
+        const tracks = cloneWithUnwrapProxy(state.tracks);
 
-        const trackIdsInTracks = new Set(tracks.keys());
-        const trackIdsInTrackChannelStrips = new Set(
-          trackChannelStripsRef.keys(),
+        const overlappingNoteIdsMap = new Map(
+          [...tracks.keys()].map((trackId) => [
+            trackId,
+            getters.OVERLAPPING_NOTE_IDS(trackId),
+          ]),
         );
-        // どちらかにしか存在しないtrackIdがある場合はエラーを投げる
-        if (
-          trackIdsInTracks.symmetricDifference(trackIdsInTrackChannelStrips)
-            .size > 0
-        ) {
-          throw new Error(
-            `The track ids are different: ${trackIdsInTracks} | ${trackIdsInTrackChannelStrips}`,
-          );
+
+        // trackChannelStripsを同期する。
+        // ここで更新されたChannelStripに既存のAudioPlayerなどを繋げる必要がある。
+        // そのため、Phraseが変わっていなくてもPhraseの更新=AudioPlayerなどの再接続は毎回行う必要がある。
+        // trackChannelStripsを同期した後、フレーズの更新が完了するまではreturnやthrowをしないこと。
+        // TODO: 良い設計を考える
+        // ref: https://github.com/VOICEVOX/voicevox/pull/2176#discussion_r1693991784
+
+        const shouldPlays = shouldPlayTracks(tracks);
+        for (const [trackId, track] of tracks) {
+          if (!trackChannelStrips.has(trackId)) {
+            const channelStrip = new ChannelStrip(audioContext);
+            channelStrip.output.connect(mainChannelStrip.input);
+            trackChannelStrips.set(trackId, channelStrip);
+          }
+
+          const channelStrip = getOrThrow(trackChannelStrips, trackId);
+          channelStrip.volume = state.experimentalSetting.enableMultiTrack
+            ? track.gain
+            : 1;
+          channelStrip.pan = state.experimentalSetting.enableMultiTrack
+            ? track.pan
+            : 0;
+          channelStrip.mute = state.experimentalSetting.enableMultiTrack
+            ? !shouldPlays.has(trackId)
+            : false;
+        }
+        for (const trackId of trackChannelStrips.keys()) {
+          if (!tracks.has(trackId)) {
+            const channelStrip = getOrThrow(trackChannelStrips, trackId);
+            channelStrip.output.disconnect();
+            trackChannelStrips.delete(trackId);
+          }
         }
 
         const singerAndFrameRates = new Map(
@@ -1594,10 +1545,7 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
           }
 
           // 重なっているノートを削除する
-          const overlappingNoteIds = getOrThrow(
-            state.overlappingNoteIds,
-            trackId,
-          );
+          const overlappingNoteIds = getOrThrow(overlappingNoteIdsMap, trackId);
           const notes = track.notes.filter(
             (value) => !overlappingNoteIds.has(value.id),
           );
@@ -1762,10 +1710,7 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
               instrument: polySynth,
               noteEvents,
             };
-            const channelStrip = getOrThrow(
-              trackChannelStripsRef,
-              phrase.trackId,
-            );
+            const channelStrip = getOrThrow(trackChannelStrips, phrase.trackId);
             polySynth.output.connect(channelStrip.input);
             transportRef.addSequence(noteSequence);
             sequences.set(phraseKey, noteSequence);
@@ -1970,10 +1915,7 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
               audioPlayer,
               audioEvents,
             };
-            const channelStrip = getOrThrow(
-              trackChannelStripsRef,
-              phrase.trackId,
-            );
+            const channelStrip = getOrThrow(trackChannelStrips, phrase.trackId);
             audioPlayer.output.connect(channelStrip.input);
             transportRef.addSequence(audioSequence);
             sequences.set(phraseKey, audioSequence);
@@ -2140,6 +2082,7 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
             sampleRate,
             renderDuration,
             withLimiter,
+            state.experimentalSetting.enableMultiTrack,
             state.tracks,
             state.phrases,
             state.singingGuides,
@@ -2284,6 +2227,7 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
         notes: notesToPaste,
         trackId: getters.SELECTED_TRACK_ID,
       });
+
       dispatch("RENDER");
       // 貼り付けたノートを選択する
       commit("DESELECT_ALL_NOTES");
@@ -2310,6 +2254,7 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
         notes: quantizedNotes,
         trackId: getters.SELECTED_TRACK_ID,
       });
+
       dispatch("RENDER");
     },
   },
@@ -2338,8 +2283,10 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
       const track = getOrThrow(state.tracks, trackId);
       track.mute = mute;
     },
-    action({ commit }, { trackId, mute }) {
+    action({ commit, dispatch }, { trackId, mute }) {
       commit("SET_TRACK_MUTE", { trackId, mute });
+
+      dispatch("RENDER");
     },
   },
 
@@ -2348,8 +2295,10 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
       const track = getOrThrow(state.tracks, trackId);
       track.solo = solo;
     },
-    action({ commit }, { trackId, solo }) {
+    action({ commit, dispatch }, { trackId, solo }) {
       commit("SET_TRACK_SOLO", { trackId, solo });
+
+      dispatch("RENDER");
     },
   },
 
@@ -2358,8 +2307,10 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
       const track = getOrThrow(state.tracks, trackId);
       track.gain = gain;
     },
-    action({ commit }, { trackId, gain }) {
+    action({ commit, dispatch }, { trackId, gain }) {
       commit("SET_TRACK_GAIN", { trackId, gain });
+
+      dispatch("RENDER");
     },
   },
 
@@ -2368,8 +2319,10 @@ export const singingStore = createPartialStore<SingingStoreTypes>({
       const track = getOrThrow(state.tracks, trackId);
       track.pan = pan;
     },
-    action({ commit }, { trackId, pan }) {
+    action({ commit, dispatch }, { trackId, pan }) {
       commit("SET_TRACK_PAN", { trackId, pan });
+
+      dispatch("RENDER");
     },
   },
 
@@ -2688,8 +2641,10 @@ export const singingCommandStore = transformCommandStore(
       mutation(draft, { trackId }) {
         singingStore.mutations.DELETE_TRACK(draft, { trackId });
       },
-      action({ commit }, { trackId }) {
+      action({ commit, dispatch }, { trackId }) {
         commit("COMMAND_DELETE_TRACK", { trackId });
+
+        dispatch("RENDER");
       },
     },
 
@@ -2706,8 +2661,10 @@ export const singingCommandStore = transformCommandStore(
       mutation(draft, { trackId, mute }) {
         singingStore.mutations.SET_TRACK_MUTE(draft, { trackId, mute });
       },
-      action({ commit }, { trackId, mute }) {
+      action({ commit, dispatch }, { trackId, mute }) {
         commit("COMMAND_SET_TRACK_MUTE", { trackId, mute });
+
+        dispatch("RENDER");
       },
     },
 
@@ -2715,8 +2672,10 @@ export const singingCommandStore = transformCommandStore(
       mutation(draft, { trackId, solo }) {
         singingStore.mutations.SET_TRACK_SOLO(draft, { trackId, solo });
       },
-      action({ commit }, { trackId, solo }) {
+      action({ commit, dispatch }, { trackId, solo }) {
         commit("COMMAND_SET_TRACK_SOLO", { trackId, solo });
+
+        dispatch("RENDER");
       },
     },
 
@@ -2724,8 +2683,10 @@ export const singingCommandStore = transformCommandStore(
       mutation(draft, { trackId, gain }) {
         singingStore.mutations.SET_TRACK_GAIN(draft, { trackId, gain });
       },
-      action({ commit }, { trackId, gain }) {
+      action({ commit, dispatch }, { trackId, gain }) {
         commit("COMMAND_SET_TRACK_GAIN", { trackId, gain });
+
+        dispatch("RENDER");
       },
     },
 
@@ -2733,8 +2694,10 @@ export const singingCommandStore = transformCommandStore(
       mutation(draft, { trackId, pan }) {
         singingStore.mutations.SET_TRACK_PAN(draft, { trackId, pan });
       },
-      action({ commit }, { trackId, pan }) {
+      action({ commit, dispatch }, { trackId, pan }) {
         commit("COMMAND_SET_TRACK_PAN", { trackId, pan });
+
+        dispatch("RENDER");
       },
     },
 
@@ -2778,21 +2741,30 @@ export const singingCommandStore = transformCommandStore(
           trackId: TrackId;
           overwrite: boolean;
         }[] = [];
-        for (const [i, track] of tracks.entries()) {
-          if (!isValidTrack(track)) {
-            throw new Error("The track is invalid.");
-          }
-          // 空のプロジェクトならトラックを上書きする
-          if (i === 0 && isTracksEmpty([...state.tracks.values()])) {
-            payload.push({
-              track,
-              trackId: getters.SELECTED_TRACK_ID,
-              overwrite: true,
-            });
-          } else {
-            const { trackId } = await dispatch("CREATE_TRACK");
-            payload.push({ track, trackId, overwrite: false });
+        if (state.experimentalSetting.enableMultiTrack) {
+          for (const [i, track] of tracks.entries()) {
+            if (!isValidTrack(track)) {
+              throw new Error("The track is invalid.");
+            }
+            // 空のプロジェクトならトラックを上書きする
+            if (i === 0 && isTracksEmpty([...state.tracks.values()])) {
+              payload.push({
+                track,
+                trackId: getters.SELECTED_TRACK_ID,
+                overwrite: true,
+              });
+            } else {
+              const { trackId } = await dispatch("CREATE_TRACK");
+              payload.push({ track, trackId, overwrite: false });
+            }
           }
+        } else {
+          // マルチトラックが無効な場合は最初のトラックのみをインポートする
+          payload.push({
+            track: tracks[0],
+            trackId: getters.SELECTED_TRACK_ID,
+            overwrite: true,
+          });
         }
 
         commit("COMMAND_IMPORT_TRACKS", {
diff --git a/src/store/type.ts b/src/store/type.ts
index 7a5dd0fe5a..d0859506cb 100644
--- a/src/store/type.ts
+++ b/src/store/type.ts
@@ -839,7 +839,6 @@ export type SingingStoreState = {
   sequencerSnapType: number;
   sequencerEditTarget: SequencerEditTarget;
   _selectedNoteIds: Set<NoteId>;
-  overlappingNoteIds: Map<TrackId, Set<NoteId>>;
   editingLyricNoteId?: NoteId;
   nowPlaying: boolean;
   volume: number;
@@ -923,6 +922,10 @@ export type SingingStoreTypes = {
     getter: Set<NoteId>;
   };
 
+  OVERLAPPING_NOTE_IDS: {
+    getter(trackId: TrackId): Set<NoteId>;
+  };
+
   SET_NOTES: {
     mutation: { notes: Note[]; trackId: TrackId };
     action(payload: { notes: Note[]; trackId: TrackId }): void;
@@ -945,9 +948,8 @@ export type SingingStoreTypes = {
     action(payload: { noteIds: NoteId[] }): void;
   };
 
-  SELECT_ALL_NOTES_IN_SELECTED_TRACK: {
-    mutation: undefined;
-    action(): void;
+  SELECT_ALL_NOTES_IN_TRACK: {
+    action({ trackId }: { trackId: TrackId }): void;
   };
 
   DESELECT_ALL_NOTES: {
@@ -1702,6 +1704,10 @@ export type ProjectStoreTypes = {
   RESET_SAVED_LAST_COMMAND_IDS: {
     mutation: void;
   };
+
+  CLEAR_UNDO_HISTORY: {
+    action(): void;
+  };
 };
 
 /*
diff --git a/src/type/preload.ts b/src/type/preload.ts
index 81f246803c..e689b43c3f 100644
--- a/src/type/preload.ts
+++ b/src/type/preload.ts
@@ -573,6 +573,7 @@ export const experimentalSettingSchema = z.object({
   enableMultiSelect: z.boolean().default(false),
   shouldKeepTuningOnTextChange: z.boolean().default(false),
   enablePitchEditInSongEditor: z.boolean().default(false),
+  enableMultiTrack: z.boolean().default(false),
 });
 
 export type ExperimentalSettingType = z.infer<typeof experimentalSettingSchema>;
diff --git "a/tests/e2e/browser/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260.spec.ts-snapshots/\343\202\271\343\202\257\343\203\252\343\203\274\343\203\263\343\202\267\343\203\247\343\203\203\343\203\210-1-browser-win32.png" "b/tests/e2e/browser/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260.spec.ts-snapshots/\343\202\271\343\202\257\343\203\252\343\203\274\343\203\263\343\202\267\343\203\247\343\203\203\343\203\210-1-browser-win32.png"
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diff --git "a/tests/e2e/browser/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260.spec.ts-snapshots/\343\202\271\343\202\257\343\203\252\343\203\274\343\203\263\343\202\267\343\203\247\343\203\203\343\203\210-2-browser-win32.png" "b/tests/e2e/browser/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260.spec.ts-snapshots/\343\202\271\343\202\257\343\203\252\343\203\274\343\203\263\343\202\267\343\203\247\343\203\203\343\203\210-2-browser-win32.png"
index 8d1d14fcf2..6b7839b4a1 100644
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diff --git "a/tests/e2e/browser/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260.spec.ts-snapshots/\343\202\271\343\202\257\343\203\252\343\203\274\343\203\263\343\202\267\343\203\247\343\203\203\343\203\210-3-browser-win32.png" "b/tests/e2e/browser/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260.spec.ts-snapshots/\343\202\271\343\202\257\343\203\252\343\203\274\343\203\263\343\202\267\343\203\247\343\203\203\343\203\210-3-browser-win32.png"
index 9d8a1807ac..5b6bc6c587 100644
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diff --git "a/tests/e2e/browser/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260.spec.ts-snapshots/\343\202\271\343\202\257\343\203\252\343\203\274\343\203\263\343\202\267\343\203\247\343\203\203\343\203\210-4-browser-win32.png" "b/tests/e2e/browser/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260/\350\250\255\345\256\232\343\203\200\343\202\244\343\202\242\343\203\255\343\202\260.spec.ts-snapshots/\343\202\271\343\202\257\343\203\252\343\203\274\343\203\263\343\202\267\343\203\247\343\203\203\343\203\210-4-browser-win32.png"
index 9d8a1807ac..5b6bc6c587 100644
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diff --git a/tests/unit/domain/sing/shouldPlayTracks.spec.ts b/tests/unit/domain/sing/shouldPlayTracks.spec.ts
new file mode 100644
index 0000000000..0dd166a18e
--- /dev/null
+++ b/tests/unit/domain/sing/shouldPlayTracks.spec.ts
@@ -0,0 +1,46 @@
+import { createDefaultTrack, shouldPlayTracks } from "@/sing/domain";
+import { Track } from "@/store/type";
+import { TrackId } from "@/type/preload";
+
+const createTrack = ({ solo, mute }: { solo: boolean; mute: boolean }) => {
+  const track = createDefaultTrack();
+  track.solo = solo;
+  track.mute = mute;
+  return track;
+};
+const toTracksMap = (tracks: Track[]) => {
+  return tracks.reduce((acc, track) => {
+    acc.set(TrackId(crypto.randomUUID()), track);
+    return acc;
+  }, new Map<TrackId, Track>());
+};
+
+describe("shouldPlayTracks", () => {
+  it("ソロのトラックが存在する場合はソロのトラックのみ再生する（ミュートは無視される）", () => {
+    const tracks = toTracksMap([
+      createTrack({ solo: false, mute: false }),
+      createTrack({ solo: false, mute: false }),
+      createTrack({ solo: true, mute: false }),
+      createTrack({ solo: true, mute: false }),
+      createTrack({ solo: false, mute: true }),
+      createTrack({ solo: false, mute: true }),
+    ]);
+    const trackIds = [...tracks.keys()];
+
+    const result = shouldPlayTracks(tracks);
+    expect([...result]).toEqual([trackIds[2], trackIds[3]]);
+  });
+
+  it("ソロのトラックが存在しない場合はミュートされていないトラックを再生する", () => {
+    const tracks = toTracksMap([
+      createTrack({ solo: false, mute: false }),
+      createTrack({ solo: false, mute: false }),
+      createTrack({ solo: false, mute: true }),
+      createTrack({ solo: false, mute: true }),
+    ]);
+    const trackIds = [...tracks.keys()];
+
+    const result = shouldPlayTracks(tracks);
+    expect([...result]).toEqual([trackIds[0], trackIds[1]]);
+  });
+});