diff --git a/optuna_dashboard/ts/components/GraphParallelCoordinate.tsx b/optuna_dashboard/ts/components/GraphParallelCoordinate.tsx
index 84f92f48..09b73666 100644
--- a/optuna_dashboard/ts/components/GraphParallelCoordinate.tsx
+++ b/optuna_dashboard/ts/components/GraphParallelCoordinate.tsx
@@ -136,7 +136,7 @@ const plotCoordinate = (
       return param!.value
     })
     const isnum = valueStrings.every((v) => {
-      return !isNaN(parseFloat(v))
+      return !isNaN(Number(v))
     })
     if (isnum) {
       const values: number[] = valueStrings.map((v) => parseFloat(v))
diff --git a/optuna_dashboard/ts/components/GraphSlice.tsx b/optuna_dashboard/ts/components/GraphSlice.tsx
index 7206e23b..221bf6df 100644
--- a/optuna_dashboard/ts/components/GraphSlice.tsx
+++ b/optuna_dashboard/ts/components/GraphSlice.tsx
@@ -186,7 +186,7 @@ const plotSlice = (
   })
 
   const isnum = valueStrings.every((v) => {
-    return !isNaN(parseFloat(v))
+    return !isNaN(Number(v))
   })
   if (isnum) {
     const valuesNum: number[] = valueStrings.map((v) => parseFloat(v))