diff --git a/cmd/suggestion/optuna/v1beta1/requirements.txt b/cmd/suggestion/optuna/v1beta1/requirements.txt
index 5e35741485d..56d92e77a27 100644
--- a/cmd/suggestion/optuna/v1beta1/requirements.txt
+++ b/cmd/suggestion/optuna/v1beta1/requirements.txt
@@ -1,4 +1,4 @@
 grpcio==1.41.1
 protobuf==3.19.1
 googleapis-common-protos==1.53.0
-optuna>=2.8.0
+optuna<3.0.0