diff --git a/optuna_dashboard/ts/components/PreferenceHistory.tsx b/optuna_dashboard/ts/components/PreferenceHistory.tsx
index 9e19bf07..db4df078 100644
--- a/optuna_dashboard/ts/components/PreferenceHistory.tsx
+++ b/optuna_dashboard/ts/components/PreferenceHistory.tsx
@@ -142,7 +142,7 @@ const ChoiceTrials: FC<{
   trials: Trial[]
   study_id: number
 }> = ({ choice, trials, study_id }) => {
-  const [isRemoved, setRemoved] = useState(choice.isRemoved)
+  const [isRemoved, setRemoved] = useState(choice.is_removed)
   const theme = useTheme()
   const worst_trials = new Set([choice.clicked])
   const action = actionCreator()
@@ -170,7 +170,7 @@ const ChoiceTrials: FC<{
         >
           {formatDate(choice.timestamp)}
         </Typography>
-        {choice.isRemoved ? (
+        {choice.is_removed ? (
           <IconButton
             disabled={!isRemoved}
             onClick={() => {
@@ -203,7 +203,7 @@ const ChoiceTrials: FC<{
           display: "flex",
           flexDirection: "row",
           flexWrap: "wrap",
-          filter: choice.isRemoved ? "brightness(0.4)" : undefined,
+          filter: choice.is_removed ? "brightness(0.4)" : undefined,
           backgroundColor: theme.palette.background.paper,
         }}
       >
diff --git a/optuna_dashboard/ts/components/PreferentialTrials.tsx b/optuna_dashboard/ts/components/PreferentialTrials.tsx
index 7fcb634f..26cc4976 100644
--- a/optuna_dashboard/ts/components/PreferentialTrials.tsx
+++ b/optuna_dashboard/ts/components/PreferentialTrials.tsx
@@ -196,7 +196,8 @@ export const PreferentialTrials: FC<{ studyDetail: StudyDetail | null }> = ({
 
   const hiddenTrials = new Set(
     studyDetail.preference_history
-      ?.map((p) => p.clicked)
+      ?.filter((h) => !h.is_removed)
+      .map((p) => p.clicked)
       .concat(studyDetail.skipped_trials) ?? []
   )
   const activeTrials = studyDetail.trials.filter(
@@ -256,7 +257,7 @@ export const PreferentialTrials: FC<{ studyDetail: StudyDetail | null }> = ({
     })
   }
   const latestHistoryId =
-    studyDetail?.preference_history?.filter((h) => !h.isRemoved).pop()?.id ??
+    studyDetail?.preference_history?.filter((h) => !h.is_removed).pop()?.id ??
     null
   if (undoHistoryId !== null && undoHistoryId !== latestHistoryId) {
     setUndoHistoryId(null)