diff --git a/src/main/db/migrations/index.ts b/src/main/db/migrations/index.ts
index bfa01e2..6c14a1b 100644
--- a/src/main/db/migrations/index.ts
+++ b/src/main/db/migrations/index.ts
@@ -7,8 +7,9 @@ import * as m005 from './m005_ai_disabled.js';
 import * as m006 from './m006_revisions.js';
 import * as m007 from './m007_fts.js';
 import * as m008 from './m008_notebooks.js';
+import * as m009 from './m009_notebook_order.js';
 
-const migrations = [m001, m002, m003, m004, m005, m006, m007, m008];
+const migrations = [m001, m002, m003, m004, m005, m006, m007, m008, m009];
 
 export function latestVersion(): number {
   return migrations[migrations.length - 1]!.version;
diff --git a/src/main/db/migrations/m009_notebook_order.ts b/src/main/db/migrations/m009_notebook_order.ts
new file mode 100644
index 0000000..ff3abfd
--- /dev/null
+++ b/src/main/db/migrations/m009_notebook_order.ts
@@ -0,0 +1,17 @@
+// v9: notebooks.sort_order 컬럼 추가 + 기존 notebooks 를 created_at 순서로 backfill.
+// NotebookList 사이드바 의 순서 변경 (T2/T3) 의 schema 기반.
+import type Database from 'better-sqlite3';
+
+export const version = 9;
+
+export function up(db: Database.Database): void {
+  db.exec(`
+    ALTER TABLE notebooks ADD COLUMN sort_order INTEGER NOT NULL DEFAULT 0;
+    CREATE INDEX idx_notebooks_sort_order ON notebooks(sort_order, created_at);
+  `);
+
+  // 기존 notebooks 를 created_at 순서로 0,1,2,... 채움
+  const rows = db.prepare(`SELECT id FROM notebooks ORDER BY created_at ASC, id ASC`).all() as Array<{ id: string }>;
+  const update = db.prepare(`UPDATE notebooks SET sort_order = ? WHERE id = ?`);
+  rows.forEach((r, idx) => update.run(idx, r.id));
+}
diff --git a/src/main/ipc/notebookApi.ts b/src/main/ipc/notebookApi.ts
index ff9c86c..fe77aaa 100644
--- a/src/main/ipc/notebookApi.ts
+++ b/src/main/ipc/notebookApi.ts
@@ -48,4 +48,6 @@ export function registerNotebookApi(deps: NotebookIpcDeps): void {
     deps.repo.moveNote(noteId, notebookId);
     return { ok: true as const };
   });
+
+  ipcMain.handle('notebook:reorder', (_e, id: string, direction: 'up' | 'down') => deps.repo.reorder(id, direction));
 }
diff --git a/src/main/repository/NotebookRepository.ts b/src/main/repository/NotebookRepository.ts
index eba56cd..d02e670 100644
--- a/src/main/repository/NotebookRepository.ts
+++ b/src/main/repository/NotebookRepository.ts
@@ -11,7 +11,7 @@ export class NotebookRepository {
               (SELECT COUNT(*) FROM notes n
                 WHERE n.notebook_id = nb.id AND n.status = 'active') AS note_count
          FROM notebooks nb
-        ORDER BY nb.name ASC`
+        ORDER BY nb.sort_order ASC, nb.name ASC`
     ).all() as Array<Record<string, unknown>>;
     return rows.map((r) => this.hydrate(r));
   }
@@ -30,12 +30,31 @@ export class NotebookRepository {
   create(input: { name: string; color?: string | null }): Notebook {
     const id = uuidv7();
     const now = new Date().toISOString();
+    const maxRow = this.db.prepare(`SELECT COALESCE(MAX(sort_order), -1) AS m FROM notebooks`).get() as { m: number };
+    const sortOrder = maxRow.m + 1;
     this.db.prepare(
-      `INSERT INTO notebooks(id, name, color, created_at, updated_at) VALUES(?,?,?,?,?)`
-    ).run(id, input.name, input.color ?? null, now, now);
+      `INSERT INTO notebooks(id, name, color, created_at, updated_at, sort_order) VALUES(?,?,?,?,?,?)`
+    ).run(id, input.name, input.color ?? null, now, now, sortOrder);
     return { id, name: input.name, color: input.color ?? null, createdAt: now, updatedAt: now, noteCount: 0 };
   }
 
+  reorder(id: string, direction: 'up' | 'down'): { ok: boolean } {
+    const cur = this.db.prepare(`SELECT sort_order FROM notebooks WHERE id = ?`).get(id) as { sort_order: number } | undefined;
+    if (!cur) return { ok: false };
+    const neighbor = direction === 'up'
+      ? this.db.prepare(`SELECT id, sort_order FROM notebooks WHERE sort_order < ? ORDER BY sort_order DESC LIMIT 1`).get(cur.sort_order)
+      : this.db.prepare(`SELECT id, sort_order FROM notebooks WHERE sort_order > ? ORDER BY sort_order ASC LIMIT 1`).get(cur.sort_order);
+    if (!neighbor) return { ok: false };  // 이미 끝
+    const n = neighbor as { id: string; sort_order: number };
+    const now = new Date().toISOString();
+    const tx = this.db.transaction(() => {
+      this.db.prepare(`UPDATE notebooks SET sort_order = ?, updated_at = ? WHERE id = ?`).run(n.sort_order, now, id);
+      this.db.prepare(`UPDATE notebooks SET sort_order = ?, updated_at = ? WHERE id = ?`).run(cur.sort_order, now, n.id);
+    });
+    tx();
+    return { ok: true };
+  }
+
   rename(id: string, name: string): void {
     const now = new Date().toISOString();
     this.db.prepare(`UPDATE notebooks SET name=?, updated_at=? WHERE id=?`).run(name, now, id);
diff --git a/src/preload/index.ts b/src/preload/index.ts
index 1ba7c6f..6d0055c 100644
--- a/src/preload/index.ts
+++ b/src/preload/index.ts
@@ -122,7 +122,8 @@ const api: InklingApi = {
     rename: (id: string, name: string) => ipcRenderer.invoke('notebook:rename', id, name),
     setColor: (id: string, color: string | null) => ipcRenderer.invoke('notebook:set-color', id, color),
     delete: (id: string) => ipcRenderer.invoke('notebook:delete', id),
-    moveNote: (noteId: string, notebookId: string) => ipcRenderer.invoke('notebook:move-note', noteId, notebookId)
+    moveNote: (noteId: string, notebookId: string) => ipcRenderer.invoke('notebook:move-note', noteId, notebookId),
+    reorder: (id: string, direction: 'up' | 'down') => ipcRenderer.invoke('notebook:reorder', id, direction)
   }
 };
 
diff --git a/src/shared/types.ts b/src/shared/types.ts
index 6e50f9f..12acfcc 100644
--- a/src/shared/types.ts
+++ b/src/shared/types.ts
@@ -274,6 +274,7 @@ export interface NotebookApi {
   setColor(id: string, color: string | null): Promise<{ ok: true }>;
   delete(id: string): Promise<{ ok: true } | { ok: false; reason: 'has_notes' | 'not_found' }>;
   moveNote(noteId: string, notebookId: string): Promise<{ ok: true }>;
+  reorder(id: string, direction: 'up' | 'down'): Promise<{ ok: boolean }>;
 }
 
 export interface InklingApi {
diff --git a/tests/unit/NotebookRepository.test.ts b/tests/unit/NotebookRepository.test.ts
index 2d83c92..80e12ee 100644
--- a/tests/unit/NotebookRepository.test.ts
+++ b/tests/unit/NotebookRepository.test.ts
@@ -112,4 +112,49 @@ describe('NotebookRepository', () => {
   it('findByName: 없으면 null', () => {
     expect(repo.findByName('없음')).toBeNull();
   });
+
+  it('list: sort_order ASC 순서로 반환', () => {
+    const a = repo.create({ name: 'A' }); // sort_order = 1 (기본=0)
+    const b = repo.create({ name: 'B' }); // sort_order = 2
+    const all = repo.list();
+    expect(all[0]!.name).toBe('기본');
+    expect(all[1]!.id).toBe(a.id);
+    expect(all[2]!.id).toBe(b.id);
+  });
+
+  it('reorder: B.up → B/기본/A 순서로 swap', () => {
+    const a = repo.create({ name: 'A' }); // sort_order=1
+    const b = repo.create({ name: 'B' }); // sort_order=2
+    // 초기: 기본(0), A(1), B(2)
+    const r = repo.reorder(b.id, 'up');
+    expect(r.ok).toBe(true);
+    const names = repo.list().map((n) => n.name);
+    expect(names).toEqual(['기본', 'B', 'A']);
+  });
+
+  it('reorder: 첫 번째 notebook up → ok:false', () => {
+    const defaultId = repo.list()[0]!.id;
+    const r = repo.reorder(defaultId, 'up');
+    expect(r.ok).toBe(false);
+  });
+
+  it('reorder: 마지막 notebook down → ok:false', () => {
+    const c = repo.create({ name: 'C' }); // sort_order=1
+    const r = repo.reorder(c.id, 'down');
+    expect(r.ok).toBe(false);
+  });
+
+  it('reorder: B.down → 기본/A/C/B 순서', () => {
+    const a = repo.create({ name: 'A' }); // sort_order=1
+    const b = repo.create({ name: 'B' }); // sort_order=2
+    const c = repo.create({ name: 'C' }); // sort_order=3
+    // 초기: 기본(0), A(1), B(2), C(3)
+    const r = repo.reorder(b.id, 'down');
+    expect(r.ok).toBe(true);
+    const names = repo.list().map((n) => n.name);
+    expect(names).toEqual(['기본', 'A', 'C', 'B']);
+    // a, c 순서 안 변함 확인
+    expect(names.indexOf('A')).toBeLessThan(names.indexOf('C'));
+    void a; void c;
+  });
 });
diff --git a/tests/unit/m009.test.ts b/tests/unit/m009.test.ts
new file mode 100644
index 0000000..d1507d9
--- /dev/null
+++ b/tests/unit/m009.test.ts
@@ -0,0 +1,28 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import Database from 'better-sqlite3';
+import { runMigrations } from '../../src/main/db/migrations/index.js';
+
+describe('m009 notebook sort_order migration', () => {
+  let db: Database.Database;
+  beforeEach(() => { db = new Database(':memory:'); db.pragma('foreign_keys = ON'); });
+  afterEach(() => { db.close(); });
+
+  it('fresh DB: default notebook 의 sort_order = 0', () => {
+    runMigrations(db);
+    const r = db.prepare(`SELECT sort_order FROM notebooks`).get() as { sort_order: number };
+    expect(r.sort_order).toBe(0);
+  });
+
+  it('새 notebook insert 시 DEFAULT 0 (caller 가 max+1 책임)', () => {
+    runMigrations(db);
+    db.prepare(`INSERT INTO notebooks(id,name,created_at,updated_at) VALUES('nb-x','회사','t','t')`).run();
+    const r = db.prepare(`SELECT sort_order FROM notebooks WHERE id='nb-x'`).get() as { sort_order: number };
+    expect(r.sort_order).toBe(0);
+  });
+
+  it('user_version reaches 9 after all migrations', () => {
+    runMigrations(db);
+    const r = db.prepare('PRAGMA user_version').get() as { user_version: number };
+    expect(r.user_version).toBe(9);
+  });
+});
diff --git a/tests/unit/migrations.test.ts b/tests/unit/migrations.test.ts
index dbf4a0b..77a4dc4 100644
--- a/tests/unit/migrations.test.ts
+++ b/tests/unit/migrations.test.ts
@@ -51,11 +51,11 @@ describe('migration v3 — soft delete columns', () => {
     db.close();
   });
 
-  it('user_version reaches latest (8)', () => {
+  it('user_version reaches latest (9)', () => {
     const db = new Database(':memory:');
     runMigrations(db);
     const row = db.prepare('PRAGMA user_version').get() as { user_version: number };
-    expect(row.user_version).toBe(8);
+    expect(row.user_version).toBe(9);
     db.close();
   });
 
diff --git a/tests/unit/notebookApi.test.ts b/tests/unit/notebookApi.test.ts
index a3685b8..535c891 100644
--- a/tests/unit/notebookApi.test.ts
+++ b/tests/unit/notebookApi.test.ts
@@ -22,7 +22,8 @@ function makeRepo() {
     setColor: vi.fn(),
     delete: vi.fn(() => ({ ok: true })),
     moveNote: vi.fn(),
-    findById: vi.fn(() => null)
+    findById: vi.fn(() => null),
+    reorder: vi.fn(() => ({ ok: true }))
   };
 }
 
@@ -96,4 +97,23 @@ describe('notebookApi IPC', () => {
     expect(repo.setColor).toHaveBeenCalledWith('id1', '#fff');
     expect(r).toEqual({ ok: true });
   });
+
+  it('notebook:reorder — repo.reorder 호출 + ok:true 전달', async () => {
+    const repo = makeRepo();
+    repo.reorder.mockReturnValue({ ok: true } as never);
+    registerNotebookApi({ repo: repo as never });
+    const h = getHandler('notebook:reorder');
+    const r = await h({}, 'nb-1', 'up');
+    expect(repo.reorder).toHaveBeenCalledWith('nb-1', 'up');
+    expect(r).toEqual({ ok: true });
+  });
+
+  it('notebook:reorder — 첫 번째 항목 up 시 ok:false 전달', async () => {
+    const repo = makeRepo();
+    repo.reorder.mockReturnValue({ ok: false } as never);
+    registerNotebookApi({ repo: repo as never });
+    const h = getHandler('notebook:reorder');
+    const r = await h({}, 'nb-first', 'up');
+    expect(r).toEqual({ ok: false });
+  });
 });