diff --git a/src/cert/AuthStorage.ts b/src/cert/AuthStorage.ts
deleted file mode 100644
index edb1e4d..0000000
--- a/src/cert/AuthStorage.ts
+++ /dev/null
@@ -1,28 +0,0 @@
-const AUTH = 'auth';
-
-export function saveAuth(token: string) {
-  const decoded = decodeToken(token);
-  let userData: { id: string; url: string };
-  userData = { id: decoded.username, url: decoded.imageUrl };
-  localStorage.setItem(AUTH, JSON.stringify(userData));
-}
-export function getAuth(): { id: string; url: string } {
-  return JSON.parse(localStorage.getItem(AUTH));
-}
-
-export function removeAuth() {
-  localStorage.removeItem(AUTH);
-}
-
-const decodeToken = (token: string) => {
-  const base64Url = token.split('.')[1];
-  const base64 = base64Url.replace(/-/g, '+').replace(/_/g, '/');
-  const jsonPayload = decodeURIComponent(
-    atob(base64)
-      .split('')
-      .map((c) => '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2))
-      .join(''),
-  );
-
-  return JSON.parse(jsonPayload);
-};
diff --git a/src/cert/TokenStorage.ts b/src/cert/TokenStorage.ts
index 3bc115e..38a0e2e 100644
--- a/src/cert/TokenStorage.ts
+++ b/src/cert/TokenStorage.ts
@@ -1,28 +1,97 @@
 const TOKEN = 'token';
-const expireDays = 5;
+
+const JWT_PART_LENGTH = 3;
+const MS_PER_SEC = 1000;
+
+enum JWTPart {
+  Header,
+  Payload,
+  Signature,
+}
+export interface JWTPayload {
+  id: string;
+  iat: number;
+  exp: number;
+}
+
+export function getJWTPart(token: string, part: JWTPart): string {
+  const parts = token.split('.');
+  if (parts.length !== JWT_PART_LENGTH) {
+    throw new Error('Invalid JWT token format.');
+  }
+  return parts[part];
+}
+
+export function isValidJWTPayload(object: any): object is JWTPayload {
+  return (
+    object !== null &&
+    typeof object === 'object' &&
+    'id' in object &&
+    typeof object.id === 'number' &&
+    'iat' in object &&
+    typeof object.iat === 'number' &&
+    'exp' in object &&
+    typeof object.exp === 'number'
+  );
+}
+
+export function parseJWTPayload(token: string): JWTPayload {
+  try {
+    const payload = decodeToken(token);
+    if (!isValidJWTPayload(payload)) {
+      throw new Error('Invalid JWTPayload');
+    }
+    return payload;
+  } catch (error) {
+    throw error;
+  }
+}
+
+export function isJWTExpired(token: string): boolean {
+  try {
+    const payload = parseJWTPayload(token);
+    return payload.exp < Date.now() / MS_PER_SEC;
+  } catch (error) {
+    console.error(error);
+    return true;
+  }
+}
 
 export function clearToken() {
-  localStorage.clear();
+  localStorage.removeItem(TOKEN);
 }
 
 export function saveToken(token: string) {
-  const tokenObj = {
-    value: token,
-    expire: Date.now() + expireDays * 24 * 60 * 60 * 1000,
-  };
-  const tokenObjString = JSON.stringify(tokenObj);
-  localStorage.setItem(TOKEN, tokenObjString);
+  localStorage.setItem(TOKEN, token);
 }
 
 export function getToken() {
-  const tokenObjString = localStorage.getItem(TOKEN);
-  if (!tokenObjString) {
-    return null;
-  }
-  const tokenObj = JSON.parse(tokenObjString);
-  if (Date.now() > tokenObj.expire) {
+  let token = localStorage.getItem(TOKEN);
+  if (token !== null && isJWTExpired(token)) {
     clearToken();
-    return null;
+    token = null;
   }
-  return tokenObj.value;
+  return token;
 }
+
+export function getDecodedToken(): { id: string; url: string } {
+  const token = localStorage.getItem(TOKEN);
+  if (!token) {
+    return { id: null, url: null };
+  }
+  const decoded = decodeToken(token);
+  return { id: decoded.username, url: decoded.imageUrl };
+}
+
+const decodeToken = (token: string) => {
+  const base64Url = token.split('.')[1];
+  const base64 = base64Url.replace(/-/g, '+').replace(/_/g, '/');
+  const jsonPayload = decodeURIComponent(
+    atob(base64)
+      .split('')
+      .map((c) => '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2))
+      .join(''),
+  );
+
+  return JSON.parse(jsonPayload);
+};
diff --git a/src/components/Auth/AuthCallback.tsx b/src/components/Auth/AuthCallback.tsx
index 47adde1..d2431aa 100644
--- a/src/components/Auth/AuthCallback.tsx
+++ b/src/components/Auth/AuthCallback.tsx
@@ -2,7 +2,7 @@ import React, { useEffect } from 'react';
 import { useLocation } from 'react-router-dom';
 import { saveToken } from '@cert/TokenStorage';
 import { useNavigate } from 'react-router-dom';
-import { saveAuth, getAuth } from '@cert/AuthStorage';
+import { getDecodedToken } from '@cert/TokenStorage';
 import GlobalLoginState from '@recoil/GlobalLoginState';
 import { useSetRecoilState } from 'recoil';
 
@@ -15,13 +15,12 @@ const AuthCallback = () => {
 
   useEffect(() => {
     saveToken(token);
-    saveAuth(token);
     setLoginState(() => {
       return {
-        id: getAuth().id,
+        id: getDecodedToken().id,
         isLogin: true,
         isAdmin: false,
-        profileUrl: getAuth().url,
+        profileUrl: getDecodedToken().url,
       };
     });
     navigate('/');
diff --git a/src/components/Auth/AuthSignUp.tsx b/src/components/Auth/AuthSignUp.tsx
index 63d5a9a..d11a8d5 100644
--- a/src/components/Auth/AuthSignUp.tsx
+++ b/src/components/Auth/AuthSignUp.tsx
@@ -5,7 +5,6 @@ import { useSetRecoilState, useRecoilValue } from 'recoil';
 import errorAlert from '@globalObj/function/errorAlert';
 import apiClient from '@service/apiClient';
 import { saveToken } from '@cert/TokenStorage';
-import { saveAuth } from '@cert/AuthStorage';
 import ProfileChangeModalShow from '@recoil/ProfileChangeModalShow';
 import SignUpProfileState from '@recoil/SignUpProfileState';
 import ProfileModal from '@auth/ProfileModal';
@@ -33,7 +32,6 @@ const AuthSignUp = () => {
       })
       .then((res) => {
         saveToken(res.data.access_token);
-        saveAuth(res.data.access_token);
         setLoginState(() => {
           return {
             id: res.data.id,
diff --git a/src/components/Review/SelectModal.tsx b/src/components/Review/SelectModal.tsx
index 2d5c0df..d806442 100644
--- a/src/components/Review/SelectModal.tsx
+++ b/src/components/Review/SelectModal.tsx
@@ -12,7 +12,7 @@ import useSWR from 'swr';
 import getAddress from '@globalObj/function/getAddress';
 import fetcher from '@globalObj/function/fetcher';
 import EmptyEvent from '@globalObj/object/EmptyEvent';
-import { getAuth } from '@cert/AuthStorage';
+import { getDecodedToken } from '@cert/TokenStorage';
 
 function SelectModal(prop: { mode: string }) {
   const { data: eventList, mutate: mutateAllEvent } = useSWR<ReviewSelectedEventType[]>(
@@ -66,7 +66,7 @@ function SelectModal(prop: { mode: string }) {
       setSelectedTeam({ [event]: memArr });
       setEventListModalShow(false);
     } else {
-      setSelectedTeam({ [event]: [{ intraId: getAuth().id, profile: getAuth().url, teamId: -1 }] });
+      setSelectedTeam({ [event]: [{ intraId: getDecodedToken().id, profile: getDecodedToken().url, teamId: -1 }] });
       setEventListModalShow(false);
     }
   };
diff --git a/src/components/Rotation/Calendar.tsx b/src/components/Rotation/Calendar.tsx
index 82f3612..9f1c90b 100644
--- a/src/components/Rotation/Calendar.tsx
+++ b/src/components/Rotation/Calendar.tsx
@@ -5,7 +5,7 @@ import timeGridPlugin from '@fullcalendar/timegrid';
 import interactionPlugin from '@fullcalendar/interaction';
 import { createEventId, getRotationArr } from './event_utils';
 import '@css/Rotation/Calendar.scss';
-import { getAuth } from '@cert/AuthStorage';
+import { getDecodedToken } from '@cert/TokenStorage';
 import { DAY_OF_SUNDAY } from './rotation_utils';
 import apiClient from '@service/apiClient';
 
@@ -16,7 +16,7 @@ const COLOR = {
 
 export default class Calendar extends React.Component {
   state = {
-    auth: getAuth(),
+    auth: getDecodedToken(),
     weekendsVisible: true,
     currentEvents: [],
   };
diff --git a/src/components/Rotation/Rotation.tsx b/src/components/Rotation/Rotation.tsx
index 1684d47..62423ad 100644
--- a/src/components/Rotation/Rotation.tsx
+++ b/src/components/Rotation/Rotation.tsx
@@ -1,6 +1,6 @@
 import React, { useEffect, useState, MouseEvent } from 'react';
 import { useNavigate } from 'react-router-dom';
-import { getAuth } from '@cert/AuthStorage';
+import { getDecodedToken } from '@cert/TokenStorage';
 import Calendar, { CalendarTileProperties } from 'react-calendar';
 import getAddress from '@globalObj/function/getAddress';
 import { getToken } from '@cert/TokenStorage';
@@ -330,7 +330,7 @@ export const Rotate = () => {
   const navigate = useNavigate();
   const currentDate = new Date();
   const initialRecord = createInitialObject(currentDate);
-  const intraId = getAuth()?.id ?? null;
+  const intraId = getDecodedToken()?.id ?? null;
   const isRotationApplicationPeriod = calculateIsRotationApplicationPeriod(currentDate);
   const [record, setRecord] = useState(() => ({ ...initialRecord }));
   const [isSubmit, setIsSubmit] = useState(false);
diff --git a/src/components/Rotation/RotationResult.tsx b/src/components/Rotation/RotationResult.tsx
index 5c03fa8..e1dc0fd 100644
--- a/src/components/Rotation/RotationResult.tsx
+++ b/src/components/Rotation/RotationResult.tsx
@@ -2,7 +2,7 @@ import React, { useState, useEffect } from 'react';
 import LoadingSpinner from './Loading';
 import { RotateUserResult } from './RotateUserResult';
 import { getRotationMonthArr } from './event_utils';
-import { getAuth } from '@cert/AuthStorage';
+import { getDecodedToken } from '@cert/TokenStorage';
 import '@css/Rotation/Rotation.scss';
 
 export const RotateResult = () => {
@@ -13,7 +13,7 @@ export const RotateResult = () => {
   date < new Date(year, nextmonth, -1) ? (month = nextmonth - 1) : nextmonth;
   const [Loading, setLoading] = useState(true);
   const [arr, setArr] = useState([]);
-  const intraId = getAuth() ? getAuth().id : null;
+  const intraId = getDecodedToken() ? getDecodedToken().id : null;
 
   const mainApi = async () => {
     setLoading(true); // api 호출 전에 true로 변경하여 로딩화면 띄우기
diff --git a/src/components/Rotation/event_utils.tsx b/src/components/Rotation/event_utils.tsx
index 9203757..ccd5d1c 100644
--- a/src/components/Rotation/event_utils.tsx
+++ b/src/components/Rotation/event_utils.tsx
@@ -1,4 +1,4 @@
-import { getAuth } from '@cert/AuthStorage';
+import { getDecodedToken } from '@cert/TokenStorage';
 import apiClient from '@service/apiClient';
 import errorAlert from '@globalObj/function/errorAlert';
 
@@ -9,7 +9,7 @@ export function createEventId() {
 }
 
 function rotatedArrAllInfo(data) {
-  const intraId = getAuth() ? getAuth().id : null;
+  const intraId = getDecodedToken() ? getDecodedToken().id : null;
   return data
     .filter((el) => !!el.year && !!el.month && !!el.day)
     .map((el) => ({
diff --git a/src/components/utils/Navbar.tsx b/src/components/utils/Navbar.tsx
index d757580..5ae152a 100644
--- a/src/components/utils/Navbar.tsx
+++ b/src/components/utils/Navbar.tsx
@@ -4,7 +4,6 @@ import { useNavigate } from 'react-router-dom';
 import { useSetRecoilState } from 'recoil';
 import GlobalLoginState from '@recoil/GlobalLoginState';
 import { clearToken, getToken } from '@cert/TokenStorage';
-import { removeAuth } from '@cert/AuthStorage';
 import { Dropdown } from './Dropdown';
 import getAddress from '@globalObj/function/getAddress';
 import apiClient from '@service/apiClient';
@@ -18,7 +17,6 @@ function Navbar() {
     apiClient
       .post('/auth/logout')
       .then((res) => {
-        removeAuth();
         clearToken();
         setLoginState(() => {
           return {
diff --git a/src/globalObj/object/EmptyEvent.ts b/src/globalObj/object/EmptyEvent.ts
index 2059be4..dc91ed5 100644
--- a/src/globalObj/object/EmptyEvent.ts
+++ b/src/globalObj/object/EmptyEvent.ts
@@ -1,4 +1,4 @@
-import { getAuth } from '@cert/AuthStorage';
+import { getDecodedToken } from '@cert/TokenStorage';
 import { ReviewSelectedEventType } from './types';
 
 function EmptyEvent(): ReviewSelectedEventType {
@@ -9,7 +9,7 @@ function EmptyEvent(): ReviewSelectedEventType {
     createdId: 1,
     intraId: 'tkim',
     isMatching: 1,
-    teamList: { 사서: [{ intraId: getAuth().id, profile: getAuth().url, teamId: -1 }] },
+    teamList: { 사서: [{ intraId: getDecodedToken().id, profile: getDecodedToken().url, teamId: -1 }] },
   };
 }
 
diff --git a/src/recoil/GlobalLoginState.ts b/src/recoil/GlobalLoginState.ts
index 43a8838..b61401e 100644
--- a/src/recoil/GlobalLoginState.ts
+++ b/src/recoil/GlobalLoginState.ts
@@ -1,13 +1,13 @@
 import { atom } from 'recoil';
 import { userData } from '@globalObj/object/types';
-import { getAuth } from '@cert/AuthStorage';
+import { getDecodedToken } from '@cert/TokenStorage';
 
-const value = getAuth()
+const value = getDecodedToken()
   ? {
       isLogin: true,
-      isAdmin: getAuth()['id'] === 'tkim',
-      id: getAuth()['id'],
-      profileUrl: getAuth()['url'],
+      isAdmin: getDecodedToken()['id'] === 'tkim',
+      id: getDecodedToken()['id'],
+      profileUrl: getDecodedToken()['url'],
     }
   : {
       isLogin: false,