diff --git a/e2e_tests/test_dashboard/test_usecases/test_preferential_optimization.py b/e2e_tests/test_dashboard/test_usecases/test_preferential_optimization.py
index 0b19fea0a..fa3317dce 100644
--- a/e2e_tests/test_dashboard/test_usecases/test_preferential_optimization.py
+++ b/e2e_tests/test_dashboard/test_usecases/test_preferential_optimization.py
@@ -9,7 +9,6 @@
 import pytest
 
 from ...test_server import make_test_server
-from ...utils import clear_inmemory_cache
 
 
 def make_test_storage() -> optuna.storages.InMemoryStorage:
@@ -44,7 +43,6 @@ def make_test_storage() -> optuna.storages.InMemoryStorage:
 
 @pytest.fixture
 def storage() -> optuna.storages.InMemoryStorage:
-    clear_inmemory_cache()
     storage = make_test_storage()
     return storage
 
diff --git a/e2e_tests/test_dashboard/test_usecases/test_study_history.py b/e2e_tests/test_dashboard/test_usecases/test_study_history.py
index f2d937bbc..6c22b16b3 100644
--- a/e2e_tests/test_dashboard/test_usecases/test_study_history.py
+++ b/e2e_tests/test_dashboard/test_usecases/test_study_history.py
@@ -3,7 +3,6 @@
 import pytest
 
 from ...test_server import make_test_server
-from ...utils import clear_inmemory_cache
 
 
 def make_test_storage() -> optuna.storages.InMemoryStorage:
@@ -24,7 +23,6 @@ def objective_single(trial: optuna.Trial) -> float:
 
 @pytest.fixture
 def storage() -> optuna.storages.InMemoryStorage:
-    clear_inmemory_cache()
     storage = make_test_storage()
     return storage
 
diff --git a/e2e_tests/test_dashboard/visual_regression_test.py b/e2e_tests/test_dashboard/visual_regression_test.py
index ab1893430..ea6ff9305 100644
--- a/e2e_tests/test_dashboard/visual_regression_test.py
+++ b/e2e_tests/test_dashboard/visual_regression_test.py
@@ -5,12 +5,10 @@
 import pytest
 
 from ..test_server import make_test_server
-from ..utils import clear_inmemory_cache
 
 
 @pytest.fixture
 def storage() -> optuna.storages.InMemoryStorage:
-    clear_inmemory_cache()
     storage = optuna.storages.InMemoryStorage()
     return storage
 
diff --git a/e2e_tests/test_server.py b/e2e_tests/test_server.py
index a15acc683..cbf65a292 100644
--- a/e2e_tests/test_server.py
+++ b/e2e_tests/test_server.py
@@ -8,6 +8,8 @@
 from optuna_dashboard import wsgi
 import pytest
 
+from .utils import clear_inmemory_cache
+
 
 def get_free_port() -> int:
     tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
@@ -28,6 +30,7 @@ def make_test_server(
     thread.start()
 
     def stop_server() -> None:
+        clear_inmemory_cache()
         httpd.shutdown()
         httpd.server_close()
         thread.join()