diff --git a/src/hooks/useEnsureGuestTable.ts b/src/hooks/useEnsureGuestTable.ts
new file mode 100644
index 00000000..e18f84b8
--- /dev/null
+++ b/src/hooks/useEnsureGuestTable.ts
@@ -0,0 +1,23 @@
+import { SAMPLE_TABLE_DATA } from '../constants/sample_table';
+import {
+  isGuestFlow,
+  setSessionCustomizeTableData,
+} from '../util/sessionStorage';
+
+export const GUEST_TABLE_ID = 'guest';
+
+/**
+ * 게스트 경로(`/:id === 'guest'`)인데 세션에 테이블 데이터가 없으면
+ * 샘플 테이블을 세션에 채워 게스트 플로우를 복구한다.
+ *
+ * 홈 버튼으로 세션이 비워진 뒤 뒤로가기로 돌아오면 게스트 판별이 풀려
+ * API 저장소로 `Number('guest')`(NaN) 조회가 나가므로, 쿼리가 저장소를
+ * 고르기 전에 동기적으로 실행되도록 렌더 중에 처리한다.
+ * 같은 페이지 인스턴스에서 id만 `guest`로 바뀌는 경우도 막기 위해 매 렌더마다
+ * 확인하며, 세션 데이터가 있으면 아무것도 하지 않으므로 반복 실행해도 안전하다.
+ */
+export function useEnsureGuestTable(id: string | undefined) {
+  if (id === GUEST_TABLE_ID && !isGuestFlow()) {
+    setSessionCustomizeTableData(SAMPLE_TABLE_DATA);
+  }
+}
diff --git a/src/page/TableOverviewPage/TableOverviewPage.tsx b/src/page/TableOverviewPage/TableOverviewPage.tsx
index 4da88f9e..fd921181 100644
--- a/src/page/TableOverviewPage/TableOverviewPage.tsx
+++ b/src/page/TableOverviewPage/TableOverviewPage.tsx
@@ -26,11 +26,13 @@ import {
   isSupportedLang,
 } from '../../util/languageRouting';
 import useAnalytics from '../../hooks/useAnalytics';
+import { useEnsureGuestTable } from '../../hooks/useEnsureGuestTable';
 
 // 토론 개요를 보여주고 공유, 수정, 시작 액션을 제공하는 페이지다.
 export default function TableOverviewPage() {
   const { t, i18n } = useTranslation();
   const { id } = useParams();
+  useEnsureGuestTable(id);
   const tableId = Number(id);
   const navigate = useNavigate();
   const { openModal, closeModal, ModalWrapper } = useModal();
diff --git a/src/page/TableOverviewPage/guestBackNavigation.test.tsx b/src/page/TableOverviewPage/guestBackNavigation.test.tsx
new file mode 100644
index 00000000..dd99ac3e
--- /dev/null
+++ b/src/page/TableOverviewPage/guestBackNavigation.test.tsx
@@ -0,0 +1,127 @@
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
+import { createMemoryRouter, RouterProvider } from 'react-router-dom';
+import { act, render, screen, waitFor } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import { GlobalPortal } from '../../util/GlobalPortal';
+import TableOverviewPage from './TableOverviewPage';
+import TableSharingPage from '../TableSharingPage/TableSharingPage';
+import { encodeDebateTableData } from '../../util/arrayEncoding';
+import { server } from '../../mocks/server';
+import { DebateTableData } from '../../types/type';
+import { SAMPLE_TABLE_DATA } from '../../constants/sample_table';
+
+const sharedTable: DebateTableData = {
+  info: {
+    name: '공유받은 테이블',
+    agenda: '공유 주제',
+    prosTeamName: '찬성',
+    consTeamName: '반대',
+  },
+  table: [
+    {
+      stance: 'PROS',
+      speechType: '입론',
+      boxType: 'NORMAL',
+      time: 60,
+      timePerTeam: null,
+      timePerSpeaking: null,
+      speaker: '1',
+      bell: [{ type: 'BEFORE_END', time: 0, count: 2 }],
+    },
+  ],
+};
+
+function renderWithRouter(initialEntry: string) {
+  const router = createMemoryRouter(
+    [
+      { path: '/share', element: <TableSharingPage /> },
+      { path: '/overview/:type/:id', element: <TableOverviewPage /> },
+      { path: '/home', element: <div>HOME</div> },
+    ],
+    { initialEntries: [initialEntry] },
+  );
+
+  render(
+    <QueryClientProvider client={new QueryClient()}>
+      <GlobalPortal.Provider>
+        <RouterProvider router={router} />
+      </GlobalPortal.Provider>
+    </QueryClientProvider>,
+  );
+
+  return router;
+}
+
+describe('비회원 테이블 개요 페이지 - 세션 데이터 유실', () => {
+  const requestedUrls: string[] = [];
+  const onRequestStart = ({ request }: { request: Request }) => {
+    requestedUrls.push(request.url);
+  };
+
+  beforeEach(() => {
+    sessionStorage.clear();
+    requestedUrls.length = 0;
+    server.events.on('request:start', onRequestStart);
+  });
+
+  afterEach(() => {
+    server.events.removeListener('request:start', onRequestStart);
+  });
+
+  it('공유 링크 -> 개요 -> 홈 -> 뒤로가기 시 NaN 조회 없이 샘플 테이블로 복구한다', async () => {
+    const router = renderWithRouter(
+      `/share?data=${encodeURIComponent(encodeDebateTableData(sharedTable))}`,
+    );
+
+    await waitFor(() =>
+      expect(router.state.location.pathname).toBe('/overview/customize/guest'),
+    );
+    await screen.findByText('공유받은 테이블');
+
+    // 헤더 홈 버튼은 게스트 세션 데이터를 삭제한다.
+    await userEvent.click(screen.getAllByLabelText('홈으로 이동')[0]);
+    await waitFor(() => expect(router.state.location.pathname).toBe('/home'));
+    expect(sessionStorage.getItem('DebateTableData')).toBeNull();
+
+    await act(async () => {
+      await router.navigate(-1);
+    });
+    expect(router.state.location.pathname).toBe('/overview/customize/guest');
+
+    await screen.findByText(SAMPLE_TABLE_DATA.info.name);
+    expect(sessionStorage.getItem('DebateTableData')).not.toBeNull();
+    expect(requestedUrls.filter((url) => url.includes('NaN'))).toEqual([]);
+  });
+
+  it('세션 데이터 없이 게스트 경로로 직접 진입해도 샘플 테이블을 보여준다', async () => {
+    renderWithRouter('/overview/customize/guest');
+
+    await screen.findByText(SAMPLE_TABLE_DATA.info.name);
+    expect(requestedUrls.filter((url) => url.includes('NaN'))).toEqual([]);
+  });
+
+  it('같은 페이지에서 회원 테이블 id가 게스트로 바뀌어도 샘플 테이블로 복구한다', async () => {
+    const router = renderWithRouter('/overview/customize/1');
+    await screen.findByText('나의 자유토론 테이블');
+
+    await act(async () => {
+      await router.navigate('/overview/customize/guest');
+    });
+
+    await screen.findByText(SAMPLE_TABLE_DATA.info.name);
+    expect(sessionStorage.getItem('DebateTableData')).not.toBeNull();
+    expect(requestedUrls.filter((url) => url.includes('NaN'))).toEqual([]);
+  });
+
+  it('세션에 게스트 데이터가 있으면 덮어쓰지 않는다', async () => {
+    sessionStorage.setItem(
+      'DebateTableData',
+      JSON.stringify({ id: -1, ...sharedTable }),
+    );
+    renderWithRouter('/overview/customize/guest');
+
+    await screen.findByText('공유받은 테이블');
+    expect(screen.queryByText(SAMPLE_TABLE_DATA.info.name)).toBeNull();
+  });
+});
diff --git a/src/page/TimerPage/TimerPage.tsx b/src/page/TimerPage/TimerPage.tsx
index 02c7a0c5..2bad5a36 100644
--- a/src/page/TimerPage/TimerPage.tsx
+++ b/src/page/TimerPage/TimerPage.tsx
@@ -20,6 +20,7 @@ import clsx from 'clsx';
 import ErrorIndicator from '../../components/ErrorIndicator/ErrorIndicator';
 import LoadingIndicator from '../../components/LoadingIndicator/LoadingIndicator';
 import { isGuestFlow } from '../../util/sessionStorage';
+import { useEnsureGuestTable } from '../../hooks/useEnsureGuestTable';
 import useAnalytics from '../../hooks/useAnalytics';
 import { consumeTemplateOrigin } from '../../util/analytics/templateOrigin';
 import {
@@ -51,6 +52,7 @@ export default function TimerPage() {
   const { t } = useTranslation();
   const [answerTime, setAnswerTime] = useState(30);
   const pathParams = useParams();
+  useEnsureGuestTable(pathParams.id);
   const tableId = Number(pathParams.id);
   const {
     openUseTooltipModal,