diff --git a/optuna_dashboard/ts/components/PreferentialGraph.tsx b/optuna_dashboard/ts/components/PreferentialGraph.tsx
index 48364598..f343cb06 100644
--- a/optuna_dashboard/ts/components/PreferentialGraph.tsx
+++ b/optuna_dashboard/ts/components/PreferentialGraph.tsx
@@ -181,6 +181,7 @@ export const PreferentialGraph: FC<{
     if (!studyDetail.is_preferential || studyDetail.preferences === undefined)
       return
     const preferences = reductionPreference(studyDetail.preferences)
+    const trialNodes = Array.from(new Set(preferences.flat()))
     const graph: ElkNode = {
       id: "root",
       layoutOptions: {
@@ -189,8 +190,8 @@ export const PreferentialGraph: FC<{
         "elk.layered.spacing.nodeNodeBetweenLayers": nodeMargin.toString(),
         "elk.spacing.nodeNode": nodeMargin.toString(),
       },
-      children: studyDetail.trials.map((trial) => ({
-        id: `${trial.number}`,
+      children: trialNodes.map((trial) => ({
+        id: `${trial}`,
         targetPosition: "top",
         sourcePosition: "bottom",
         width: nodeWidth,
@@ -207,7 +208,7 @@ export const PreferentialGraph: FC<{
       .then((layoutedGraph) => {
         setNodes(
           layoutedGraph.children?.map((node, index) => {
-            const trial = studyDetail.trials[index]
+            const trial = studyDetail.trials[trialNodes[index]]
             return {
               id: `${trial.number}`,
               type: "note",