diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6b40f09..b99a54f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -51,6 +51,27 @@ jobs:
             exit 1
           fi
 
+  test-integration:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      - uses: ./.github/actions/setup-node
+      - name: Create test env file
+        run: |
+          cat <<'EOF' > .env.test
+          POSTGRES_HOST=localhost
+          POSTGRES_VERSION=15
+          POSTGRES_USER=core_test
+          POSTGRES_PASSWORD=core_test
+          POSTGRES_DB=core_test
+          POSTGRES_PORT=5433
+          EOF
+      - run: docker compose --env-file .env.test -f docker-compose.test.yml up -d --wait
+      - run: npm run test:integration
+      - if: always()
+        run: docker compose --env-file .env.test -f docker-compose.test.yml down
+
   build:
     runs-on: ubuntu-latest
     timeout-minutes: 10
diff --git a/docker-compose.test.yml b/docker-compose.test.yml
new file mode 100644
index 0000000..0a7aa6a
--- /dev/null
+++ b/docker-compose.test.yml
@@ -0,0 +1,16 @@
+services:
+  test-db:
+    image: "postgres:${POSTGRES_VERSION:-15}" #15のバージョン
+    ports:
+      - "${POSTGRES_PORT}:5432"
+    environment:
+      POSTGRES_USER: ${POSTGRES_USER}
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
+      POSTGRES_DB: ${POSTGRES_DB}
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U ${POSTGRES_USER} -d ${POSTGRES_DB}"]
+      interval: 2s
+      timeout: 5s
+      retries: 10
+    tmpfs:
+      - /var/lib/postgresql/data
diff --git a/package-lock.json b/package-lock.json
index 19aee33..9ce7353 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1977,6 +1977,22 @@
         }
       }
     },
+    "node_modules/@voidzero-dev/vite-plus-test/node_modules/typescript": {
+      "version": "5.9.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.9.3.tgz",
+      "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "peer": true,
+      "bin": {
+        "tsc": "bin/tsc",
+        "tsserver": "bin/tsserver"
+      },
+      "engines": {
+        "node": ">=14.17"
+      }
+    },
     "node_modules/@voidzero-dev/vite-plus-win32-arm64-msvc": {
       "version": "0.1.14",
       "resolved": "https://registry.npmjs.org/@voidzero-dev/vite-plus-win32-arm64-msvc/-/vite-plus-win32-arm64-msvc-0.1.14.tgz",
@@ -3389,6 +3405,22 @@
         }
       }
     },
+    "node_modules/vite-plus/node_modules/typescript": {
+      "version": "5.9.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.9.3.tgz",
+      "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "peer": true,
+      "bin": {
+        "tsc": "bin/tsc",
+        "tsserver": "bin/tsserver"
+      },
+      "engines": {
+        "node": ">=14.17"
+      }
+    },
     "node_modules/which": {
       "version": "2.0.2",
       "resolved": "https://registry.npmjs.org/which/-/which-2.0.2.tgz",
diff --git a/package.json b/package.json
index c7b43f2..22c8a54 100644
--- a/package.json
+++ b/package.json
@@ -32,6 +32,9 @@
     "prepare": "npm run build",
     "test": "vp test",
     "test:watch": "vp test watch",
+    "test:integration": "vp test --config vite.config.integration.ts",
+    "test:integration:up": "docker compose --env-file .env.test -f docker-compose.test.yml up -d --wait && npm run test:integration",
+    "test:integration:down": "docker compose --env-file .env.test -f docker-compose.test.yml down",
     "typecheck": "tsc --noEmit",
     "check": "vp check",
     "lint": "vp lint",
diff --git a/tests/helpers/config.ts b/tests/helpers/config.ts
new file mode 100644
index 0000000..73672f3
--- /dev/null
+++ b/tests/helpers/config.ts
@@ -0,0 +1,49 @@
+import { readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+import { parseEnv } from "node:util";
+
+const TEST_ENV_PATH = fileURLToPath(new URL("../../.env.test", import.meta.url));
+
+function loadTestEnv(): Record<string, string | undefined> {
+	return parseEnv(readFileSync(TEST_ENV_PATH, "utf8"));
+}
+
+function requireEnv(env: Record<string, string | undefined>, name: string): string {
+	const value = env[name];
+	if (!value) {
+		throw new Error(`${name} is not set in .env.test`);
+	}
+	return value;
+}
+
+const loadedEnv = loadTestEnv();
+
+for (const [key, value] of Object.entries(loadedEnv)) {
+	process.env[key] = value;
+}
+
+export const testConfig = {
+	db: {
+		host: requireEnv(loadedEnv, "POSTGRES_HOST"),
+		port: Number(requireEnv(loadedEnv, "POSTGRES_PORT")),
+		name: requireEnv(loadedEnv, "POSTGRES_DB"),
+		user: requireEnv(loadedEnv, "POSTGRES_USER"),
+		password: requireEnv(loadedEnv, "POSTGRES_PASSWORD"),
+	},
+} as const;
+
+const databaseUrl = new URL(
+	`postgresql://${testConfig.db.host}:${testConfig.db.port}/${testConfig.db.name}`,
+);
+databaseUrl.username = testConfig.db.user;
+databaseUrl.password = testConfig.db.password;
+
+export const TEST_DATABASE_URL = databaseUrl.toString();
+
+process.env.DATABASE_URL = TEST_DATABASE_URL;
+
+export const testProcessEnv: NodeJS.ProcessEnv = {
+	...process.env,
+	...loadedEnv,
+	DATABASE_URL: TEST_DATABASE_URL,
+};
diff --git a/tests/helpers/db.ts b/tests/helpers/db.ts
new file mode 100644
index 0000000..9c12145
--- /dev/null
+++ b/tests/helpers/db.ts
@@ -0,0 +1,79 @@
+import { execSync } from "node:child_process";
+import { getTableName, isTable } from "drizzle-orm";
+import { drizzle } from "drizzle-orm/node-postgres";
+import { escapeIdentifier, Pool } from "pg";
+import type { DrizzleClient } from "#infrastructure/drizzle/client";
+import * as schema from "#infrastructure/drizzle/schema";
+import { TEST_DATABASE_URL, testConfig, testProcessEnv } from "./config";
+
+/** スキーマ定義から _prisma_migrations を除いた全テーブル名を動的に取得 */
+const EXCLUDED_TABLES = new Set(["_prisma_migrations"]);
+// TODO: #143 が解決されたら _prisma_migrations の暫定除外を削除する。
+
+function getApplicationTableNames(): string[] {
+	const tableNames: string[] = [];
+
+	for (const value of Object.values(schema) as unknown[]) {
+		if (!isTable(value)) continue;
+		tableNames.push(getTableName(value));
+	}
+
+	return tableNames.filter((name) => !EXCLUDED_TABLES.has(name));
+}
+
+let pool: Pool | null = null;
+let client: DrizzleClient | null = null;
+
+/** テスト用プールを取得（なければ作成） */
+function getPool(): Pool {
+	if (!pool) {
+		pool = new Pool({ connectionString: TEST_DATABASE_URL });
+	}
+	return pool;
+}
+
+/** テスト用Drizzleクライアントを取得（アサーション用） */
+export function getTestClient(): DrizzleClient {
+	if (!client) {
+		client = drizzle(getPool(), { schema });
+	}
+	return client;
+}
+
+/** マイグレーションを実行してスキーマを最新にする */
+export async function setupTestDatabase(): Promise<void> {
+	const p = getPool();
+
+	// 接続先がテスト用DBであることを確認（本番DBへの誤接続を防止）
+	const result = await p.query("SELECT current_database()");
+	const dbName = result.rows[0].current_database;
+	if (dbName !== testConfig.db.name) {
+		throw new Error(
+			`テスト用DBではないDBに接続しています: "${dbName}"。接続先が ${testConfig.db.name} であることを確認してください。`,
+		);
+	}
+
+	// drizzle-kit pushでスキーマを同期（マイグレーションファイル不要で現在のスキーマを反映）
+	execSync("vp run db:push -- --force", {
+		env: testProcessEnv,
+		stdio: "pipe",
+	});
+}
+
+/** 全アプリケーションテーブルをTRUNCATEする */
+export async function cleanDatabase(): Promise<void> {
+	const tableNames = getApplicationTableNames();
+	if (tableNames.length === 0) return;
+	const p = getPool();
+	const quotedTableNames = tableNames.map(escapeIdentifier);
+	await p.query(`TRUNCATE ${quotedTableNames.join(", ")} CASCADE`);
+}
+
+/** テスト用プールを閉じる */
+export async function teardownTestDatabase(): Promise<void> {
+	if (pool) {
+		await pool.end();
+		pool = null;
+		client = null;
+	}
+}
diff --git a/tests/helpers/globalSetup.ts b/tests/helpers/globalSetup.ts
new file mode 100644
index 0000000..3370b5b
--- /dev/null
+++ b/tests/helpers/globalSetup.ts
@@ -0,0 +1,9 @@
+import { setupTestDatabase, teardownTestDatabase } from "./db";
+
+export async function setup() {
+	await setupTestDatabase();
+}
+
+export async function teardown() {
+	await teardownTestDatabase();
+}
diff --git a/tests/helpers/setupIntegration.ts b/tests/helpers/setupIntegration.ts
new file mode 100644
index 0000000..8461c31
--- /dev/null
+++ b/tests/helpers/setupIntegration.ts
@@ -0,0 +1,7 @@
+import { beforeEach } from "vite-plus/test";
+import "./config";
+import { cleanDatabase } from "./db";
+
+beforeEach(async () => {
+	await cleanDatabase();
+});
diff --git a/tests/infrastructure/drizzle/runInTransaction.integration.test.ts b/tests/infrastructure/drizzle/runInTransaction.integration.test.ts
new file mode 100644
index 0000000..4a8d35e
--- /dev/null
+++ b/tests/infrastructure/drizzle/runInTransaction.integration.test.ts
@@ -0,0 +1,57 @@
+import { describe, expect, it } from "vite-plus/test";
+import { eq } from "drizzle-orm";
+import { getTestClient } from "../../helpers/db";
+import { getClient, runInTransaction } from "#infrastructure/drizzle/client";
+import { events } from "#infrastructure/drizzle/schema";
+
+function testEvent(id: string, name: string) {
+	const now = new Date().toISOString();
+	return { id, name, date: now, updatedAt: now };
+}
+
+describe("runInTransaction", () => {
+	it("複数の書き込みがすべて永続化される", async () => {
+		await runInTransaction(async () => {
+			const client = getClient();
+			await client.insert(events).values(testEvent("test-1", "Event 1"));
+			await client.insert(events).values(testEvent("test-2", "Event 2"));
+		});
+
+		const db = getTestClient();
+		const rows = await db.select().from(events).where(eq(events.id, "test-1"));
+		const rows2 = await db.select().from(events).where(eq(events.id, "test-2"));
+		expect(rows).toHaveLength(1);
+		expect(rows2).toHaveLength(1);
+	});
+
+	it("途中で例外が発生したら全て巻き戻る", async () => {
+		await expect(
+			runInTransaction(async () => {
+				const client = getClient();
+				await client.insert(events).values(testEvent("test-rollback", "Should not persist"));
+				throw new Error("intentional error");
+			}),
+		).rejects.toThrow("intentional error");
+
+		const db = getTestClient();
+		const rows = await db.select().from(events).where(eq(events.id, "test-rollback"));
+		expect(rows).toHaveLength(0);
+	});
+
+	it("ネスト時に内側のrunInTransactionが新しいトランザクションを開始せず、外側の失敗で全体が巻き戻る", async () => {
+		await expect(
+			runInTransaction(async () => {
+				await runInTransaction(async () => {
+					const client = getClient();
+					await client.insert(events).values(testEvent("test-nested", "Nested write"));
+				});
+
+				throw new Error("outer failure");
+			}),
+		).rejects.toThrow("outer failure");
+
+		const db = getTestClient();
+		const rows = await db.select().from(events).where(eq(events.id, "test-nested"));
+		expect(rows).toHaveLength(0);
+	});
+});
diff --git a/vite.config.integration.ts b/vite.config.integration.ts
new file mode 100644
index 0000000..37bc993
--- /dev/null
+++ b/vite.config.integration.ts
@@ -0,0 +1,20 @@
+import { fileURLToPath } from "node:url";
+import { defineConfig } from "vite-plus";
+
+export default defineConfig({
+	resolve: {
+		alias: {
+			"#domain": fileURLToPath(new URL("./src/domain", import.meta.url)),
+			"#application": fileURLToPath(new URL("./src/application", import.meta.url)),
+			"#infrastructure": fileURLToPath(new URL("./src/infrastructure", import.meta.url)),
+		},
+	},
+	test: {
+		include: ["tests/**/*.integration.test.ts"],
+		globalSetup: ["tests/helpers/globalSetup.ts"],
+		setupFiles: ["tests/helpers/setupIntegration.ts"],
+		testTimeout: 30_000,
+		hookTimeout: 30_000,
+		fileParallelism: false,
+	},
+});
diff --git a/vite.config.ts b/vite.config.ts
index ee3df83..9e4f5cb 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -11,6 +11,7 @@ export default defineConfig({
 	},
 	test: {
 		include: ["tests/**/*.test.ts"],
+		exclude: ["tests/**/*.integration.test.ts"],
 	},
 	lint: {
 		ignorePatterns: ["dist/**", "drizzle/**", "example/**"],