diff --git a/optuna_dashboard/artifact/boto3.py b/optuna_dashboard/artifact/boto3.py
index 2ef8766b..a4656c7a 100644
--- a/optuna_dashboard/artifact/boto3.py
+++ b/optuna_dashboard/artifact/boto3.py
@@ -24,7 +24,7 @@ class Boto3Backend:
 
        This class is deprecated. Please use `optuna.artifacts.Boto3ArtifactStore
        <https://optuna.readthedocs.io/en/latest/reference/generated/optuna.artifacts.
-       Boto3ArtifactStore.html>`_ instead.",
+       Boto3ArtifactStore.html>`_ instead.
 
     Example:
        .. code-block:: python
diff --git a/optuna_dashboard/artifact/file_system.py b/optuna_dashboard/artifact/file_system.py
index b84b9ed4..d298e9d6 100644
--- a/optuna_dashboard/artifact/file_system.py
+++ b/optuna_dashboard/artifact/file_system.py
@@ -19,7 +19,7 @@ class FileSystemBackend:
 
        This class is deprecated. Please use `optuna.artifacts.FileSystemArtifactStore
        <https://optuna.readthedocs.io/en/latest/reference/generated/optuna.artifacts.
-       FileSystemArtifactStore.html>`_ instead.",
+       FileSystemArtifactStore.html>`_ instead.
 
     Example:
        .. code-block:: python