diff --git a/src/apis/post/queries.ts b/src/apis/post/queries.ts
index bdf7f886..1a05776e 100644
--- a/src/apis/post/queries.ts
+++ b/src/apis/post/queries.ts
@@ -31,6 +31,7 @@ export const useGetPostQuery = (id: number) =>
   useQuery({
     queryKey: ['getPost', id],
     queryFn: () => getPost(id),
+    retry: false,
     enabled: typeof id === 'number',
     select: data => ({
       ...data,
diff --git a/src/constants/message.ts b/src/constants/message.ts
index 272a42a8..626c04cd 100644
--- a/src/constants/message.ts
+++ b/src/constants/message.ts
@@ -4,3 +4,7 @@ export const VALID_NICKNAME_MESSAGE = {
   MIN_LENGTH_ERROR: '닉네임은 2자 이상 입력해주세요.',
   EMPTY_ERROR: '닉네임을 입력해주세요!'
 } as const
+
+export const ALERT_MESSAGE = {
+  LEAVE_PAGE: `사이트에서 나가시겠습니까?\n변경사항이 저장되지 않을 수 있습니다.`
+} as const
diff --git a/src/hooks/index.ts b/src/hooks/index.ts
index bc8c8846..80fbad3a 100644
--- a/src/hooks/index.ts
+++ b/src/hooks/index.ts
@@ -3,3 +3,4 @@ export * from './useAuth'
 export * from './useModal'
 export * from './result/useCategoryFilterList'
 export * from './result/useSelectBoxFilter'
+export * from './usePreventLeavePage'
diff --git a/src/hooks/usePreventLeavePage.ts b/src/hooks/usePreventLeavePage.ts
new file mode 100644
index 00000000..80a000e1
--- /dev/null
+++ b/src/hooks/usePreventLeavePage.ts
@@ -0,0 +1,36 @@
+import { useRouter } from 'next/router'
+import { useEffect } from 'react'
+import { ALERT_MESSAGE } from '@constants'
+
+const handleBeforeUnload = (e: BeforeUnloadEvent) => {
+  e.returnValue = ALERT_MESSAGE.LEAVE_PAGE
+
+  return ALERT_MESSAGE.LEAVE_PAGE
+}
+
+export const usePreventLeavePage = (isPrevent = true) => {
+  const router = useRouter()
+
+  useEffect(() => {
+    const handleBeforeChangeRoute = (url: string) => {
+      if (router.pathname !== url && !confirm(ALERT_MESSAGE.LEAVE_PAGE)) {
+        router.events.emit('routeChangeError')
+
+        throw `사이트 변경 취소`
+      }
+    }
+
+    if (!isPrevent) {
+      return
+    }
+
+    window.addEventListener('beforeunload', handleBeforeUnload)
+    router.events.on('routeChangeStart', handleBeforeChangeRoute)
+
+    // eslint-disable-next-line consistent-return
+    return () => {
+      window.removeEventListener('beforeunload', handleBeforeUnload)
+      router.events.off('routeChangeStart', handleBeforeChangeRoute)
+    }
+  }, [isPrevent])
+}
diff --git a/src/pages/post/[postId]/index.tsx b/src/pages/post/[postId]/index.tsx
index d6232a31..9e6d6df9 100644
--- a/src/pages/post/[postId]/index.tsx
+++ b/src/pages/post/[postId]/index.tsx
@@ -46,8 +46,8 @@ const PostDetailPage = ({ postId }: Props): ReactElement => {
   const updateTradeStatusMutation = useUpdateTradeStatusMutation()
   const deletePostMutation = useDeletePostMutation(postId)
 
-  const [tradeStatus, setTradeStatus] = useState<TradeStatusCodes>()
   const router = useRouter()
+  const [tradeStatus, setTradeStatus] = useState<TradeStatusCodes>()
 
   const tradeStatusDialog = useModal()
   const deleteModal = useModal()
@@ -74,6 +74,12 @@ const PostDetailPage = ({ postId }: Props): ReactElement => {
     router.replace('/')
   }
 
+  if (getPostQuery.isError) {
+    router.push('/403')
+
+    return <></>
+  }
+
   return (
     <>
       <Layout>
diff --git a/src/pages/post/index.tsx b/src/pages/post/index.tsx
index a5f165a9..b7fe37aa 100644
--- a/src/pages/post/index.tsx
+++ b/src/pages/post/index.tsx
@@ -11,6 +11,7 @@ import {
   Divider
 } from '@offer-ui/react'
 import type { ImageInfo, InputProps } from '@offer-ui/react'
+import { isEqual } from 'lodash'
 import type { GetServerSideProps } from 'next'
 import { useRouter } from 'next/router'
 import type { ReactElement } from 'react'
@@ -26,7 +27,7 @@ import {
 } from '@apis'
 import { PostForm } from '@components'
 import { TRADE_TYPES, PRODUCT_CONDITIONS, TRADE_STATUS } from '@constants'
-import { useResponsive } from '@hooks'
+import { useAuth, usePreventLeavePage, useResponsive } from '@hooks'
 
 type PostFormState = Partial<
   Omit<CreatePostReq, 'price' | 'thumbnailImageUrl' | 'imageUrls'>
@@ -77,9 +78,14 @@ const PostPage = ({ type, editPostId }: Props): ReactElement => {
   const createUploadImagesMutation = useCreateUploadImagesMutation()
   const getCategoriesQuery = useGetCategoriesQuery()
   const updatePostMutation = useUpdatePostMutation()
-  const router = useRouter()
 
+  const initialPostForm: PostFormState = getPostQuery.data?.postForm || {}
   const [postForm, setPostForm] = useState<PostFormState>({})
+  const hasChanged = !isEqual(initialPostForm, postForm)
+  const canPosting = hasChanged && isCompleteForm(postForm)
+  const router = useRouter()
+  const { user } = useAuth()
+  usePreventLeavePage(hasChanged)
 
   const InputSize = useResponsive<InputProps, 'width'>({
     desktop: '278px',
@@ -97,7 +103,7 @@ const PostPage = ({ type, editPostId }: Props): ReactElement => {
   }
 
   const handlePostProduct = async () => {
-    if (!isCompleteForm(postForm)) {
+    if (!canPosting) {
       return
     }
 
@@ -143,10 +149,23 @@ const PostPage = ({ type, editPostId }: Props): ReactElement => {
 
   useEffect(() => {
     if (getPostQuery.data) {
+      const { seller } = getPostQuery.data
+
+      if (seller.id !== user.id) {
+        router.push('/403')
+        return
+      }
+
       setPostForm(getPostQuery.data.postForm)
     }
   }, [getPostQuery.data])
 
+  if (getPostQuery.isError) {
+    router.push('/403')
+
+    return <></>
+  }
+
   return (
     <StyledPostPage>
       <StyledSellText styleType="headline02B" tag="p">
@@ -246,7 +265,7 @@ const PostPage = ({ type, editPostId }: Props): ReactElement => {
       </StyledFormWrapper>
       <StyledButtonWrapper>
         <Button
-          disabled={!isCompleteForm(postForm)}
+          disabled={!canPosting}
           styleType="solidPrimary"
           onClick={handlePostProduct}>
           확인