diff --git a/optuna_dashboard/_importance.py b/optuna_dashboard/_importance.py
index e6ba0b047..8ab434e88 100644
--- a/optuna_dashboard/_importance.py
+++ b/optuna_dashboard/_importance.py
@@ -27,7 +27,7 @@
 
 
 try:
-    from optuna.importance import PedAnovaImportanceEvaluator
+    from optuna.importance import PedAnovaImportanceEvaluator # type: ignore[attr-defined]
 except ImportError:
     _logger.warning("optuna>=3.6.0 is required for PedAnovaImportanceEvaluator.")
     PedAnovaImportanceEvaluator = None  # type: ignore