diff --git a/frontend/src/apis/TimeTableAPI.ts b/frontend/src/apis/TimeTableAPI.ts
index e607b176..eb02cb74 100644
--- a/frontend/src/apis/TimeTableAPI.ts
+++ b/frontend/src/apis/TimeTableAPI.ts
@@ -63,6 +63,7 @@ export const usePostTimeSlot = () => {
 
   return {
     createTimeSlot: mutation.mutate,
+    createTimeSlotAsync: mutation.mutateAsync,
     error: mutation.error,
   };
 };
diff --git a/frontend/src/features/timeTable/components/AvailableTimeSlot.tsx b/frontend/src/features/timeTable/components/AvailableTimeSlot.tsx
index 3dcc8415..edd11cfc 100644
--- a/frontend/src/features/timeTable/components/AvailableTimeSlot.tsx
+++ b/frontend/src/features/timeTable/components/AvailableTimeSlot.tsx
@@ -8,7 +8,6 @@ import type {
 } from "@/features/timeTable/TimeTable.type";
 import { getTimeSlotGridStyle } from "@/features/timeTable/TimeTable.style";
 import { CloseIcon } from "@/assets/icons";
-import { useState } from "react";
 import { isBeforeToday } from "@/features/calender/Calender.util";
 
 const { color, typography } = theme;
@@ -30,8 +29,6 @@ const AvailableTimeSlot = ({
   onDelete,
   disabled = false,
 }: AvailableTimeSlotProps) => {
-  const [hovered, setHovered] = useState(false);
-
   const isPastDate = isBeforeToday(slot.rentalDate);
 
   const canInteract =
@@ -45,21 +42,19 @@ const AvailableTimeSlot = ({
 
   return (
     <div
-      onMouseEnter={() => canInteract && setHovered(true)}
-      onMouseLeave={() => canInteract && setHovered(false)}
       css={[
         getTimeSlotGridStyle(slot, selectedWeek),
-        getSlotContainerStyle(isPastDate, variant, canInteract, hovered),
+        getSlotContainerStyle(isPastDate, variant, canInteract),
       ]}
     >
       {variant === "default" && (
         <>
           <header>유휴 시간</header>
-          {canInteract && hovered && (
+          {canInteract && (
             <button
               type="button"
               onClick={handleDeleteClick}
-              css={DeleteButtonStyle(hovered)}
+              css={DeleteButtonStyle}
             >
               <CloseIcon fill={color.Maincolor.primary} />
             </button>
@@ -79,7 +74,6 @@ export default AvailableTimeSlot;
 const BaseSlotStyle = (
   variant: "default" | "preview",
   canInteract: boolean,
-  hovered: boolean,
 ) => css`
   position: relative;
   height: calc(100% - 16px); // 상하 margin 제외
@@ -91,19 +85,20 @@ const BaseSlotStyle = (
   flex-direction: column;
   justify-content: space-between;
   pointer-events: ${canInteract ? "auto" : "none"};
+  transition:
+    transform 140ms ease,
+    box-shadow 140ms ease,
+    filter 140ms ease;
 
-  ${hovered &&
-  canInteract &&
+  ${canInteract &&
   variant === "default" &&
   css`
-    transition:
-      transform 140ms ease,
-      box-shadow 140ms ease,
-      filter 140ms ease;
-    will-change: transform, box-shadow;
-    transform: translateY(-2px) scale(1.01);
-    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
-    filter: brightness(0.98);
+    &:hover {
+      will-change: transform, box-shadow;
+      transform: translateY(-2px) scale(1.01);
+      box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
+      filter: brightness(0.98);
+    }
   `}
 `;
 
@@ -126,9 +121,8 @@ const getSlotContainerStyle = (
   isPastDate: boolean,
   variant: "default" | "preview",
   canInteract: boolean,
-  hovered: boolean,
 ) => {
-  const styles = [BaseSlotStyle(variant, canInteract, hovered)];
+  const styles = [BaseSlotStyle(variant, canInteract)];
 
   if (isPastDate) {
     styles.push(PastSlotStyle);
@@ -138,11 +132,16 @@ const getSlotContainerStyle = (
   return styles;
 };
 
-const DeleteButtonStyle = (hovered: boolean) => css`
+const DeleteButtonStyle = css`
   position: absolute;
   top: 16px;
   right: 20px;
   border: none;
   cursor: pointer;
-  color: ${hovered ? color.Maincolor.primary : color.GrayScale.gray4};
+  opacity: 0;
+  color: ${color.Maincolor.primary};
+
+  *:hover > & {
+    opacity: 1;
+  }
 `;
diff --git a/frontend/src/features/timeTable/components/TimeTable.tsx b/frontend/src/features/timeTable/components/TimeTable.tsx
index 766217f0..40f6eb85 100644
--- a/frontend/src/features/timeTable/components/TimeTable.tsx
+++ b/frontend/src/features/timeTable/components/TimeTable.tsx
@@ -79,12 +79,11 @@ const TimeTable = ({
   const slotsDisabled = Boolean(previewSlot);
 
   const queryClient = useQueryClient();
-  const { createTimeSlot, error: postError } = usePostTimeSlot();
+  const { createTimeSlotAsync, error: postError } = usePostTimeSlot();
   const {
     timeSlotData,
     isFetching,
     error: fetchError,
-    refetch,
   } = useGetTimeSlot(selectedCarId, nextWeekKey);
 
   // Error 관련 상태
@@ -109,16 +108,24 @@ const TimeTable = ({
       setPreviewSlot: setPreviewSlot,
     });
 
-  // selectedCarId나 selectedWeek이 변경되면 draft 상태 초기화 및 애니메이션 처리
+  // selectedCarId나 selectedWeek이 변경되면 상태 초기화 및 애니메이션 처리
+  // 기존 Effect 1(draft 초기화 + displayWeek 전환)과 Effect 2(handleCancelClick)를 병합
+  // deps: onEditModeChange, queryClient, queryKey는 트리거 목적이 아니므로 의도적 제외
   useEffect(() => {
+    onEditModeChange?.(false);
     setShowSlots(false);
-    setTimeSlotsDraft([]);
     setPreviewSlot(null);
 
-    const rafId = window.requestAnimationFrame(() => {
+    const cachedSlotData =
+      queryClient.getQueryData<TimeSlotAPIResponse>(queryKey);
+    setTimeSlotsDraft(cachedSlotData?.data ?? []);
+
+    const rafId = requestAnimationFrame(() => {
       setDisplayWeek(selectedWeek);
+      setShowSlots(true);
     });
-    return () => window.cancelAnimationFrame(rafId);
+    return () => cancelAnimationFrame(rafId);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [selectedCarId, selectedWeek]);
 
   // 새로운 데이터가 로드되면 draft 상태 초기화
@@ -142,17 +149,12 @@ const TimeTable = ({
     onEditModeChange?.(false);
   }, [queryClient, queryKey, onEditModeChange]);
 
-  useEffect(() => {
-    handleCancelClick();
-  }, [selectedWeek, selectedCarId, handleCancelClick]);
-
-  const handleSaveClick = () => {
-    createTimeSlot({
+  const handleSaveClick = async () => {
+    await createTimeSlotAsync({
       selectedCarId,
       weekKey,
       timeSlots: timeSlotsDraft,
     });
-    void refetch();
     onEditModeChange?.(false);
   };
 
diff --git a/frontend/src/features/timeTable/services/slotMerger.ts b/frontend/src/features/timeTable/services/slotMerger.ts
index af2c927a..8151b0e9 100644
--- a/frontend/src/features/timeTable/services/slotMerger.ts
+++ b/frontend/src/features/timeTable/services/slotMerger.ts
@@ -3,6 +3,7 @@ import {
   formatTimeToNumber,
 } from "@/features/calender/Calender.util";
 import type { AvailableTimeSlotType } from "@/features/timeTable/TimeTable.type";
+import { slotUtils } from "@/features/timeTable/utils/slotUtils";
 
 export const slotMerger = {
   /**
@@ -53,7 +54,8 @@ export const slotMerger = {
     if (overlappingSlots.length > 0) {
       const mergedSlot = slotMerger.mergeSlots(newSlot, overlappingSlots);
       const remainingSlots = availableTimeSlots.filter(
-        (slot) => !overlappingSlots.includes(slot),
+        (slot) =>
+          !overlappingSlots.some((o) => slotUtils.isSameSlot(o, slot)),
       );
 
       return [mergedSlot, ...remainingSlots];
diff --git a/frontend/src/features/timeTable/utils/slotUtils.ts b/frontend/src/features/timeTable/utils/slotUtils.ts
index 34839ebd..23558d87 100644
--- a/frontend/src/features/timeTable/utils/slotUtils.ts
+++ b/frontend/src/features/timeTable/utils/slotUtils.ts
@@ -17,30 +17,4 @@ export const slotUtils = {
       a.rentalEndTime === b.rentalEndTime
     );
   },
-
-  /**
-   * 슬롯 배열에서 특정 슬롯을 찾아 제거합니다.
-   * @param slots 슬롯 배열
-   * @param targetSlot 제거할 대상 슬롯
-   * @returns 대상 슬롯이 제거된 새로운 배열
-   */
-  removeSlot: (
-    slots: AvailableTimeSlotType[],
-    targetSlot: AvailableTimeSlotType,
-  ): AvailableTimeSlotType[] => {
-    return slots.filter((slot) => !slotUtils.isSameSlot(slot, targetSlot));
-  },
-
-  /**
-   * 슬롯 배열에 새로운 슬롯을 추가합니다.
-   * @param slots 기존 슬롯 배열
-   * @param newSlot 추가할 새로운 슬롯
-   * @returns 새로운 슬롯이 추가된 배열
-   */
-  addSlot: (
-    slots: AvailableTimeSlotType[],
-    newSlot: AvailableTimeSlotType,
-  ): AvailableTimeSlotType[] => {
-    return [newSlot, ...slots];
-  },
 };