diff --git a/.github/workflows/windows-tests.yml b/.github/workflows/windows-tests.yml
index 599b7bb08eb..f5a450c86ad 100644
--- a/.github/workflows/windows-tests.yml
+++ b/.github/workflows/windows-tests.yml
@@ -118,6 +118,8 @@ jobs:
         pip install --progress-bar off .[optional]
         pip install --progress-bar off .[integration]
         pip install "distributed<2023.3.2"
+        # TODO(nabenabe0928): Remove the version constraint on Torch.
+        pip install "torch<2.2.0"
 
     - name: Output installed packages
       run: |
diff --git a/optuna/integration/pytorch_distributed.py b/optuna/integration/pytorch_distributed.py
index 51e56cd8eb9..c30c4116f07 100644
--- a/optuna/integration/pytorch_distributed.py
+++ b/optuna/integration/pytorch_distributed.py
@@ -21,7 +21,7 @@
 with try_import() as _imports:
     import torch
     import torch.distributed as dist
-    from torch.distributed import ProcessGroup  # type: ignore[attr-defined]
+    from torch.distributed import ProcessGroup
 
 
 if TYPE_CHECKING:
diff --git a/tests/artifacts_tests/test_boto3.py b/tests/artifacts_tests/test_boto3.py
index d703945fe11..fef599cf7f7 100644
--- a/tests/artifacts_tests/test_boto3.py
+++ b/tests/artifacts_tests/test_boto3.py
@@ -11,10 +11,10 @@
 
 
 try:
-    from moto import mock_aws
+    # TODO(nabenabe0928): Replace it with `from moto import mock_aws` after dropping Python3.7.
+    from moto import mock_aws  # type: ignore[attr-defined]
 except ImportError:
-    from moto import mock_s3 as mock_aws
-
+    from moto import mock_s3 as mock_aws  # type: ignore[attr-defined,no-redef]
 
 if TYPE_CHECKING:
     from collections.abc import Iterator