diff --git a/optuna_dashboard/_app.py b/optuna_dashboard/_app.py
index eaab1ba6..812201ad 100644
--- a/optuna_dashboard/_app.py
+++ b/optuna_dashboard/_app.py
@@ -222,10 +222,8 @@ def create_app(
         ) = get_cached_extra_study_property(study_id, trials)
 
         plotly_graph_objects = get_plotly_graph_objects(system_attrs)
-        trials_id2number = {trial._trial_id: trial.number for trial in trials}
-        skipped_trials = [
-            trials_id2number[trial_id] for trial_id in get_skipped_trial_ids(system_attrs)
-        ]
+        skipped_trial_ids = get_skipped_trial_ids(system_attrs)
+        skipped_trial_numbers = [t.number for t in trials if t._trial_id in skipped_trial_ids]
         return serialize_study_detail(
             summary,
             best_trials,
@@ -235,7 +233,7 @@ def create_app(
             union_user_attrs,
             has_intermediate_values,
             plotly_graph_objects,
-            skipped_trials,
+            skipped_trial_numbers,
         )
 
     @app.get("/api/studies/<study_id:int>/param_importances")
diff --git a/optuna_dashboard/_serializer.py b/optuna_dashboard/_serializer.py
index e1840df9..81544ea8 100644
--- a/optuna_dashboard/_serializer.py
+++ b/optuna_dashboard/_serializer.py
@@ -136,7 +136,7 @@ def serialize_study_detail(
     union_user_attrs: list[tuple[str, bool]],
     has_intermediate_values: bool,
     plotly_graph_objects: dict[str, str],
-    skipped_trials: list[int],
+    skipped_trial_numbers: list[int],
 ) -> dict[str, Any]:
     serialized: dict[str, Any] = {
         "name": summary.study_name,
@@ -174,7 +174,7 @@ def serialize_study_detail(
     if serialized["is_preferential"]:
         serialized["preference_history"] = serialize_preference_history(system_attrs)
         serialized["preferences"] = get_preferences(system_attrs)
-        serialized["skipped_trials"] = skipped_trials
+        serialized["skipped_trial_numbers"] = skipped_trial_numbers
     serialized["plotly_graph_objects"] = [
         {"id": id_, "graph_object": graph_object}
         for id_, graph_object in plotly_graph_objects.items()
diff --git a/optuna_dashboard/ts/action.ts b/optuna_dashboard/ts/action.ts
index 0e1c9420..41afdadb 100644
--- a/optuna_dashboard/ts/action.ts
+++ b/optuna_dashboard/ts/action.ts
@@ -16,6 +16,8 @@ import {
   deleteArtifactAPI,
   reportPreferenceAPI,
   skipPreferentialTrialAPI,
+  removePreferentialHistoryAPI,
+  restorePreferentialHistoryAPI,
   reportFeedbackComponentAPI,
 } from "./apiClient"
 import {
@@ -587,11 +589,11 @@ export const actionCreator = () => {
   }
 
   const updatePreference = (
-    study_id: number,
+    studyId: number,
     candidates: number[],
     clicked: number
   ) => {
-    reportPreferenceAPI(study_id, candidates, clicked).catch((err) => {
+    reportPreferenceAPI(studyId, candidates, clicked).catch((err) => {
       const reason = err.response?.data.reason
       enqueueSnackbar(`Failed to report preference. Reason: ${reason}`, {
         variant: "error",
@@ -609,7 +611,6 @@ export const actionCreator = () => {
       console.log(err)
     })
   }
-
   const updateFeedbackComponent = (
     studyId: number,
     compoennt_type: FeedbackComponentType
@@ -632,6 +633,52 @@ export const actionCreator = () => {
       })
   }
 
+  const removePreferentialHistory = (studyId: number, historyId: string) => {
+    removePreferentialHistoryAPI(studyId, historyId)
+      .then(() => {
+        const newStudy = Object.assign({}, studyDetails[studyId])
+        newStudy.preference_history = newStudy.preference_history?.map((h) =>
+          h.id === historyId ? { ...h, is_removed: true } : h
+        )
+        const removed = newStudy.preference_history
+          ?.filter((h) => h.id === historyId)
+          .pop()?.preferences
+        newStudy.preferences = newStudy.preferences?.filter(
+          (p) => !removed?.some((r) => r[0] === p[0] && r[1] === p[1])
+        )
+        setStudyDetailState(studyId, newStudy)
+      })
+      .catch((err) => {
+        const reason = err.response?.data.reason
+
+        enqueueSnackbar(`Failed to switch history. Reason: ${reason}`, {
+          variant: "error",
+        })
+        console.log(err)
+      })
+  }
+  const restorePreferentialHistory = (studyId: number, historyId: string) => {
+    restorePreferentialHistoryAPI(studyId, historyId)
+      .then(() => {
+        const newStudy = Object.assign({}, studyDetails[studyId])
+        newStudy.preference_history = newStudy.preference_history?.map((h) =>
+          h.id === historyId ? { ...h, is_removed: false } : h
+        )
+        const restored = newStudy.preference_history
+          ?.filter((h) => h.id === historyId)
+          .pop()?.preferences
+        newStudy.preferences = newStudy.preferences?.concat(restored ?? [])
+        setStudyDetailState(studyId, newStudy)
+      })
+      .catch((err) => {
+        const reason = err.response?.data.reason
+        enqueueSnackbar(`Failed to switch history. Reason: ${reason}`, {
+          variant: "error",
+        })
+        console.log(err)
+      })
+  }
+
   return {
     updateAPIMeta,
     updateStudyDetail,
@@ -653,6 +700,8 @@ export const actionCreator = () => {
     saveTrialUserAttrs,
     updatePreference,
     skipPreferentialTrial,
+    removePreferentialHistory,
+    restorePreferentialHistory,
     updateFeedbackComponent,
   }
 }
diff --git a/optuna_dashboard/ts/apiClient.ts b/optuna_dashboard/ts/apiClient.ts
index 60c461db..c0065bd3 100644
--- a/optuna_dashboard/ts/apiClient.ts
+++ b/optuna_dashboard/ts/apiClient.ts
@@ -55,10 +55,9 @@ const convertTrialResponse = (res: TrialResponse): Trial => {
   }
 }
 
-interface PreferenceHistoryResponce {
+interface PreferenceHistoryResponse {
   history: {
     id: string
-    preference_id: string
     candidates: number[]
     clicked: number
     mode: PreferenceFeedbackMode
@@ -69,11 +68,10 @@ interface PreferenceHistoryResponce {
 }
 
 const convertPreferenceHistory = (
-  res: PreferenceHistoryResponce
+  res: PreferenceHistoryResponse
 ): PreferenceHistory => {
   return {
     id: res.history.id,
-    preference_id: res.history.preference_id,
     candidates: res.history.candidates,
     clicked: res.history.clicked,
     feedback_mode: res.history.mode,
@@ -99,10 +97,10 @@ interface StudyDetailResponse {
   objective_names?: string[]
   form_widgets?: FormWidgets
   preferences?: [number, number][]
-  preference_history?: PreferenceHistoryResponce[]
+  preference_history?: PreferenceHistoryResponse[]
   plotly_graph_objects: PlotlyGraphObject[]
   feedback_component_type: FeedbackComponentType
-  skipped_trials?: number[]
+  skipped_trial_numbers?: number[]
 }
 
 export const getStudyDetailAPI = (
@@ -144,7 +142,7 @@ export const getStudyDetailAPI = (
           convertPreferenceHistory
         ),
         plotly_graph_objects: res.data.plotly_graph_objects,
-        skipped_trials: res.data.skipped_trials ?? [],
+        skipped_trial_numbers: res.data.skipped_trial_numbers ?? [],
       }
     })
 }
@@ -379,6 +377,27 @@ export const skipPreferentialTrialAPI = (
     })
 }
 
+export const removePreferentialHistoryAPI = (
+  studyId: number,
+  historyUuid: string
+): Promise<void> => {
+  return axiosInstance
+    .delete<void>(`/api/studies/${studyId}/preference/${historyUuid}`)
+    .then(() => {
+      return
+    })
+}
+export const restorePreferentialHistoryAPI = (
+  studyId: number,
+  historyUuid: string
+): Promise<void> => {
+  return axiosInstance
+    .post<void>(`/api/studies/${studyId}/preference/${historyUuid}`)
+    .then(() => {
+      return
+    })
+}
+
 export const reportFeedbackComponentAPI = (
   studyId: number,
   component_type: FeedbackComponentType
diff --git a/optuna_dashboard/ts/components/PreferenceHistory.tsx b/optuna_dashboard/ts/components/PreferenceHistory.tsx
index e9c4948c..6aa67317 100644
--- a/optuna_dashboard/ts/components/PreferenceHistory.tsx
+++ b/optuna_dashboard/ts/components/PreferenceHistory.tsx
@@ -10,12 +10,15 @@ import {
 import ClearIcon from "@mui/icons-material/Clear"
 import IconButton from "@mui/material/IconButton"
 import OpenInFullIcon from "@mui/icons-material/OpenInFull"
+import RestoreFromTrashIcon from "@mui/icons-material/RestoreFromTrash"
+import DeleteIcon from "@mui/icons-material/Delete"
 import Modal from "@mui/material/Modal"
 import { red } from "@mui/material/colors"
 
 import { TrialListDetail } from "./TrialList"
 import { getArtifactUrlPath } from "./PreferentialTrials"
 import { formatDate } from "../dateUtil"
+import { actionCreator } from "../action"
 import { useStudyDetailValue } from "../state"
 import { PreferentialOutputComponent } from "./PreferentialOutputComponent"
 
@@ -157,33 +160,75 @@ const CandidateTrial: FC<{
   )
 }
 
-const ChoiceTrials: FC<{ choice: PreferenceHistory; trials: Trial[] }> = ({
-  choice,
-  trials,
-}) => {
+const ChoiceTrials: FC<{
+  choice: PreferenceHistory
+  trials: Trial[]
+  studyId: number
+}> = ({ choice, trials, studyId }) => {
+  const [isRemoved, setRemoved] = useState(choice.is_removed)
   const theme = useTheme()
   const worst_trials = new Set([choice.clicked])
+  const action = actionCreator()
 
   return (
     <Box
       sx={{
         marginBottom: theme.spacing(4),
+        position: "relative",
       }}
     >
-      <Typography
-        variant="h6"
-        sx={{
-          fontWeight: theme.typography.fontWeightLight,
-        }}
-      >
-        {formatDate(choice.timestamp)}
-      </Typography>
       <Box
         sx={{
           display: "flex",
           flexDirection: "row",
           flexWrap: "wrap",
         }}
+      >
+        <Typography
+          variant="h6"
+          sx={{
+            fontWeight: theme.typography.fontWeightLight,
+            margin: "auto 0",
+          }}
+        >
+          {formatDate(choice.timestamp)}
+        </Typography>
+        {choice.is_removed ? (
+          <IconButton
+            disabled={!isRemoved}
+            onClick={() => {
+              setRemoved(false)
+              action.restorePreferentialHistory(studyId, choice.id)
+            }}
+            sx={{
+              margin: `auto ${theme.spacing(2)}`,
+            }}
+          >
+            <RestoreFromTrashIcon />
+          </IconButton>
+        ) : (
+          <IconButton
+            disabled={isRemoved}
+            onClick={() => {
+              setRemoved(true)
+              action.removePreferentialHistory(studyId, choice.id)
+            }}
+            sx={{
+              margin: `auto ${theme.spacing(2)}`,
+            }}
+          >
+            <DeleteIcon />
+          </IconButton>
+        )}
+      </Box>
+      <Box
+        sx={{
+          display: "flex",
+          flexDirection: "row",
+          flexWrap: "wrap",
+          filter: choice.is_removed ? "brightness(0.4)" : undefined,
+          backgroundColor: theme.palette.background.paper,
+        }}
       >
         {choice.candidates.map((trial_num, index) => (
           <CandidateTrial
@@ -234,6 +279,7 @@ export const PreferenceHistory: FC<{ studyDetail: StudyDetail | null }> = ({
           key={choice.id}
           choice={choice}
           trials={studyDetail.trials}
+          studyId={studyDetail.id}
         />
       ))}
     </Box>
diff --git a/optuna_dashboard/ts/components/PreferentialGraph.tsx b/optuna_dashboard/ts/components/PreferentialGraph.tsx
index 4f2c1059..e30974c1 100644
--- a/optuna_dashboard/ts/components/PreferentialGraph.tsx
+++ b/optuna_dashboard/ts/components/PreferentialGraph.tsx
@@ -203,6 +203,7 @@ export const PreferentialGraph: FC<{
     if (!studyDetail.is_preferential || studyDetail.preferences === undefined)
       return
     const preferences = reductionPreference(studyDetail.preferences)
+    const trialNodes = Array.from(new Set(preferences.flat()))
     const graph: ElkNode = {
       id: "root",
       layoutOptions: {
@@ -211,8 +212,8 @@ export const PreferentialGraph: FC<{
         "elk.layered.spacing.nodeNodeBetweenLayers": nodeMargin.toString(),
         "elk.spacing.nodeNode": nodeMargin.toString(),
       },
-      children: studyDetail.trials.map((trial) => ({
-        id: `${trial.number}`,
+      children: trialNodes.map((trial) => ({
+        id: `${trial}`,
         targetPosition: "top",
         sourcePosition: "bottom",
         width: nodeWidth,
@@ -229,7 +230,7 @@ export const PreferentialGraph: FC<{
       .then((layoutedGraph) => {
         setNodes(
           layoutedGraph.children?.map((node, index) => {
-            const trial = studyDetail.trials[index]
+            const trial = studyDetail.trials[trialNodes[index]]
             return {
               id: `${trial.number}`,
               type: "note",
diff --git a/optuna_dashboard/ts/components/PreferentialTrials.tsx b/optuna_dashboard/ts/components/PreferentialTrials.tsx
index 27f3a8d5..b3934a80 100644
--- a/optuna_dashboard/ts/components/PreferentialTrials.tsx
+++ b/optuna_dashboard/ts/components/PreferentialTrials.tsx
@@ -21,10 +21,11 @@ import {
 import IconButton from "@mui/material/IconButton"
 import OpenInFullIcon from "@mui/icons-material/OpenInFull"
 import ReplayIcon from "@mui/icons-material/Replay"
+import { red } from "@mui/material/colors"
+import UndoIcon from "@mui/icons-material/Undo"
 import ClearIcon from "@mui/icons-material/Clear"
 import SettingsIcon from "@mui/icons-material/Settings"
 import FullscreenIcon from "@mui/icons-material/Fullscreen"
-import red from "@mui/material/colors/red"
 
 import { actionCreator } from "../action"
 import { TrialListDetail } from "./TrialList"
@@ -399,6 +400,8 @@ export const PreferentialTrials: FC<{ studyDetail: StudyDetail | null }> = ({
   studyDetail,
 }) => {
   const theme = useTheme()
+  const action = actionCreator()
+  const [undoHistoryFlag, setUndoHistoryFlag] = useState(false)
   const [openThreejsArtifactModal, renderThreejsArtifactModal] =
     useThreejsArtifactModal()
   const [displayTrials, setDisplayTrials] = useState<DisplayTrials>({
@@ -414,8 +417,9 @@ export const PreferentialTrials: FC<{ studyDetail: StudyDetail | null }> = ({
 
   const hiddenTrials = new Set(
     studyDetail.preference_history
-      ?.map((p) => p.clicked)
-      .concat(studyDetail.skipped_trials) ?? []
+      ?.filter((h) => !h.is_removed)
+      .map((p) => p.clicked)
+      .concat(studyDetail.skipped_trial_numbers) ?? []
   )
   const activeTrials = studyDetail.trials.filter(
     (t) =>
@@ -468,34 +472,75 @@ export const PreferentialTrials: FC<{ studyDetail: StudyDetail | null }> = ({
       }
     })
   }
+  const visibleTrial = (num: number) => {
+    setDisplayTrials((prev) => {
+      const index = prev.clicked.findIndex((n) => n === num)
+      if (index === -1) {
+        return prev
+      }
+      const clicked = [...prev.clicked]
+      clicked[index] = -1
+      return {
+        display: prev.display,
+        clicked: clicked,
+      }
+    })
+  }
+  const latestHistoryId =
+    studyDetail?.preference_history?.filter((h) => !h.is_removed).pop()?.id ??
+    null
 
   return (
-    <Box
-      padding={theme.spacing(2)}
-      sx={{
-        position: "relative",
-      }}
-    >
-      <IconButton
-        sx={{
-          position: "absolute",
-          top: 0,
-          right: 0,
-          margin: theme.spacing(1),
-        }}
-        onClick={() => setSettingShown(true)}
-      >
-        <SettingsIcon />
-      </IconButton>
-      <Typography
-        variant="h4"
-        sx={{
-          marginBottom: theme.spacing(2),
-          fontWeight: theme.typography.fontWeightBold,
-        }}
-      >
-        Which trial is the worst?
-      </Typography>
+    <Box padding={theme.spacing(2)}>
+      <Box display="flex">
+        <Typography
+          variant="h4"
+          sx={{
+            fontWeight: theme.typography.fontWeightBold,
+          }}
+        >
+          Which trial is the worst?
+        </Typography>
+        <Box
+          display="flex"
+          sx={{
+            marginLeft: "auto",
+          }}
+        >
+          <Button
+            variant="outlined"
+            disabled={latestHistoryId === null || undoHistoryFlag}
+            sx={{
+              marginRight: theme.spacing(2),
+            }}
+            startIcon={<UndoIcon />}
+            onClick={() => {
+              if (latestHistoryId === null) {
+                return
+              }
+              setUndoHistoryFlag(true)
+              const clicked = studyDetail.preference_history
+                ?.filter((h) => h.id === latestHistoryId)
+                ?.pop()?.clicked
+              if (clicked !== undefined) visibleTrial(clicked)
+              action.removePreferentialHistory(studyDetail.id, latestHistoryId)
+              setUndoHistoryFlag(false)
+            }}
+          >
+            Undo
+          </Button>
+          <Button
+            variant="outlined"
+            sx={{
+              marginRight: theme.spacing(2),
+            }}
+            startIcon={<SettingsIcon />}
+            onClick={() => setSettingShown(true)}
+          >
+            Settings
+          </Button>
+        </Box>
+      </Box>
       <Box sx={{ display: "flex", flexDirection: "row", flexWrap: "wrap" }}>
         {displayTrials.display.map((t, index) => {
           const trial = activeTrials.find((trial) => trial.number === t)
@@ -553,9 +598,10 @@ export const PreferentialTrials: FC<{ studyDetail: StudyDetail | null }> = ({
               <IconButton
                 sx={{
                   position: "absolute",
-                  marginTop: theme.spacing(2),
-                  marginRight: theme.spacing(2),
+                  top: theme.spacing(2),
+                  right: theme.spacing(2),
                 }}
+                onClick={() => setDetailTrial(null)}
               >
                 <ClearIcon />
               </IconButton>
diff --git a/optuna_dashboard/ts/types/index.d.ts b/optuna_dashboard/ts/types/index.d.ts
index e23c22e3..3e883e14 100644
--- a/optuna_dashboard/ts/types/index.d.ts
+++ b/optuna_dashboard/ts/types/index.d.ts
@@ -218,7 +218,7 @@ type StudyDetail = {
   preferences?: [number, number][]
   preference_history?: PreferenceHistory[]
   plotly_graph_objects: PlotlyGraphObject[]
-  skipped_trials: number[]
+  skipped_trial_numbers: number[]
 }
 
 type StudyDetails = {
@@ -230,7 +230,6 @@ type StudyParamImportance = {
 }
 type PreferenceHistory = {
   id: string
-  preference_id: string
   candidates: number[]
   clicked: number
   feedback_mode: PreferenceFeedbackMode