diff --git a/optuna_dashboard/ts/components/GraphRank.tsx b/optuna_dashboard/ts/components/GraphRank.tsx
index 1267da81..527b71a0 100644
--- a/optuna_dashboard/ts/components/GraphRank.tsx
+++ b/optuna_dashboard/ts/components/GraphRank.tsx
@@ -29,8 +29,8 @@ interface RankPlotInfo {
   ytitle: string
   xtype: plotly.AxisType
   ytype: plotly.AxisType
-  xvalues: (string | number | boolean)[]
-  yvalues: (string | number | boolean)[]
+  xvalues: (string | number)[]
+  yvalues: (string | number)[]
   colors: number[]
   is_feasible: boolean[]
   hovertext: string[]
@@ -213,8 +213,8 @@ const getRankPlotInfo = (
   const xAxis = getAxisInfo(filteredTrials, xParam)
   const yAxis = getAxisInfo(filteredTrials, yParam)
 
-  let xValues: (string | number | boolean)[] = []
-  let yValues: (string | number | boolean)[] = []
+  let xValues: (string | number)[] = []
+  let yValues: (string | number)[] = []
   const zValues: number[] = []
   const isFeasible: boolean[] = []
   const hovertext: string[] = []
@@ -349,12 +349,8 @@ const plotRank = (
     template: colorTheme,
   }
 
-  const xValues = rankPlotInfo.xvalues.map((value) =>
-    typeof value === "boolean" ? (value ? 1 : 0) : value
-  )
-  const yValues = rankPlotInfo.yvalues.map((value) =>
-    typeof value === "boolean" ? (value ? 1 : 0) : value
-  )
+  const xValues = rankPlotInfo.xvalues
+  const yValues = rankPlotInfo.yvalues
 
   const plotData: Partial<plotly.PlotData>[] = [
     {
diff --git a/tslib/react/src/utils/graph.ts b/tslib/react/src/utils/graph.ts
index e996431e..2572c75d 100644
--- a/tslib/react/src/utils/graph.ts
+++ b/tslib/react/src/utils/graph.ts
@@ -7,7 +7,7 @@ export type AxisInfo = {
   isLog: boolean
   isCat: boolean
   indices: (string | number)[]
-  values: (string | number | boolean | null)[]
+  values: (string | number | null)[]
 }
 
 // biome-ignore lint/suspicious/noExplicitAny: Accept any array.