diff --git a/optuna_dashboard/ts/components/StudyDetail.tsx b/optuna_dashboard/ts/components/StudyDetail.tsx
index 2a52e47e..ff532a7c 100644
--- a/optuna_dashboard/ts/components/StudyDetail.tsx
+++ b/optuna_dashboard/ts/components/StudyDetail.tsx
@@ -632,7 +632,7 @@ export const TrialTable: FC<{ studyDetail: StudyDetail | null }> = ({
           if (firstVal === secondVal) {
             return 0
           } else if (firstVal && secondVal) {
-            return firstVal < secondVal ? 1 : -1
+            return Number(firstVal) < Number(secondVal) ? 1 : -1
           } else if (firstVal) {
             return -1
           } else {