diff --git a/src/modules/auths/login.js b/src/modules/auths/login.js
index f8e4308c..8181c991 100644
--- a/src/modules/auths/login.js
+++ b/src/modules/auths/login.js
@@ -27,7 +27,7 @@ const login = (req, sid, id, oid, name) => {
 const logout = (req) => {
   // 로그아웃 전 socket.io 소켓들 연결부터 끊기
   const io = req.app.get("io");
-  if (io) io.in(req.session.id).disconnectSockets(true);
+  if (io) io.in(`session-${req.session.id}`).disconnectSockets(true);
 
   req.session.destroy((err) => {
     if (err) logger.error(err);
diff --git a/src/modules/populates/rooms.js b/src/modules/populates/rooms.js
index 18cbedf9..7243d648 100644
--- a/src/modules/populates/rooms.js
+++ b/src/modules/populates/rooms.js
@@ -7,7 +7,7 @@ const roomPopulateOption = [
   { path: "to", select: "_id koName enName" },
   {
     path: "part",
-    select: "-_id user settlementStatus",
+    select: "-_id user settlementStatus readAt",
     populate: { path: "user", select: "_id id name nickname profileImageUrl" },
   },
 ];
@@ -29,13 +29,14 @@ const formatSettlement = (
   roomObject.part = roomObject.part.map((participantSubDocument) => {
     const { _id, name, nickname, profileImageUrl } =
       participantSubDocument.user;
-    const { settlementStatus } = participantSubDocument;
+    const { settlementStatus, readAt } = participantSubDocument;
     return {
       _id,
       name,
       nickname,
       profileImageUrl,
       isSettlement: includeSettlement ? settlementStatus : undefined,
+      readAt: readAt ?? roomObject.madeat,
     };
   });
   roomObject.settlementTotal = includeSettlement
diff --git a/src/modules/socket.js b/src/modules/socket.js
index 3da4370e..bca99161 100644
--- a/src/modules/socket.js
+++ b/src/modules/socket.js
@@ -206,6 +206,30 @@ const emitChatEvent = async (io, chat) => {
   }
 };
 
+const emitUpdateEvent = async (io, roomId) => {
+  try {
+    // 방의 모든 사용자에게 socket 메세지 업데이트 이벤트를 발생시킵니다.
+    if (!io || !roomId) {
+      throw new IllegalArgumentsException();
+    }
+
+    const { name, part } = await roomModel.findById(roomId, "name part");
+
+    if (!name || !part) {
+      throw new IllegalArgumentsException();
+    }
+
+    part.forEach(({ user }) => io.in(`user-${user}`).emit("chat_update"), {
+      roomId,
+    });
+
+    return true;
+  } catch (err) {
+    logger.error(err);
+    return false;
+  }
+};
+
 // https://socket.io/how-to/use-with-express-session 참고
 const startSocketServer = (server) => {
   const io = new Server(server, {
@@ -266,5 +290,6 @@ const startSocketServer = (server) => {
 module.exports = {
   transformChatsForRoom,
   emitChatEvent,
+  emitUpdateEvent,
   startSocketServer,
 };
diff --git a/src/modules/stores/mongo.js b/src/modules/stores/mongo.js
index 998aecdd..119e0c0d 100755
--- a/src/modules/stores/mongo.js
+++ b/src/modules/stores/mongo.js
@@ -35,6 +35,7 @@ const participantSchema = Schema({
     enum: ["not-departed", "paid", "send-required", "sent"],
     default: "not-departed",
   },
+  readAt: { type: Date },
 });
 
 const deviceTokenSchema = Schema({
@@ -118,6 +119,7 @@ const locationSchema = Schema({
   latitude: { type: Number }, // 이후 required: true 로 수정 필요
   longitude: { type: Number }, // 이후 required: true 로 수정 필요
 });
+
 const chatSchema = Schema({
   roomId: { type: Schema.Types.ObjectId, ref: "Room", required: true },
   type: {
diff --git a/src/routes/chats.js b/src/routes/chats.js
index 812755f6..f689348c 100644
--- a/src/routes/chats.js
+++ b/src/routes/chats.js
@@ -54,6 +54,17 @@ router.post(
   chatsHandlers.sendChatHandler
 );
 
+/**
+ * 채팅 읽은 시각 업데이트 요청을 처리합니다.
+ * 같은 방에 있는 user들에게 업데이트를 요청합니다.
+ */
+router.post(
+  "/read",
+  body("roomId").isMongoId(),
+  validator,
+  chatsHandlers.readChatHandler
+);
+
 // 채팅 이미지를 업로드할 수 있는 Presigned-url을 발급합니다.
 router.post(
   "/uploadChatImg/getPUrl",
diff --git a/src/services/chats.js b/src/services/chats.js
index 4a76b1a4..abcbd073 100644
--- a/src/services/chats.js
+++ b/src/services/chats.js
@@ -1,7 +1,12 @@
 const { chatModel, userModel, roomModel } = require("../modules/stores/mongo");
 const { chatPopulateOption } = require("../modules/populates/chats");
+const { roomPopulateOption } = require("../modules/populates/rooms");
 const aws = require("../modules/stores/aws");
-const { transformChatsForRoom, emitChatEvent } = require("../modules/socket");
+const {
+  transformChatsForRoom,
+  emitChatEvent,
+  emitUpdateEvent,
+} = require("../modules/socket");
 const logger = require("../modules/logger");
 
 const chatCount = 60;
@@ -170,6 +175,51 @@ const sendChatHandler = async (req, res) => {
   }
 };
 
+const readChatHandler = async (req, res) => {
+  try {
+    const io = req.app.get("io");
+    const { userId } = req;
+    const { roomId } = req.body;
+    const user = await userModel.findOne({ id: userId });
+
+    if (!userId || !user) {
+      return res.status(500).send("Chat/read : internal server error");
+    }
+    if (!io) {
+      return res.status(403).send("Chat/read : socket did not connected");
+    }
+
+    const roomObject = await roomModel
+      .findOneAndUpdate(
+        {
+          _id: roomId,
+          part: {
+            $elemMatch: {
+              user: user._id,
+            },
+          },
+        },
+        {
+          $set: { "part.$[updater].readAt": req.timestamp },
+        },
+        {
+          new: true,
+          arrayFilters: [{ "updater.user": { $eq: user._id } }],
+        }
+      )
+      .lean();
+
+    if (!roomObject) {
+      return res.status(404).send("Chat/read : cannot find room info");
+    }
+
+    if (await emitUpdateEvent(io, roomId)) res.json({ result: true });
+    else res.status(500).send("Chat/read : failed to emit socket events");
+  } catch (e) {
+    res.status(500).send("Chat/read : internal server error");
+  }
+};
+
 const uploadChatImgGetPUrlHandler = async (req, res) => {
   try {
     const { type, roomId } = req.body;
@@ -284,4 +334,5 @@ module.exports = {
   sendChatHandler,
   uploadChatImgGetPUrlHandler,
   uploadChatImgDoneHandler,
+  readChatHandler,
 };