diff --git a/.changeset/jolly-tables-tan.md b/.changeset/jolly-tables-tan.md
new file mode 100644
index 0000000..8d42262
--- /dev/null
+++ b/.changeset/jolly-tables-tan.md
@@ -0,0 +1,5 @@
+---
+"@yamatomo/playwright": patch
+---
+
+fix: Correct subprocess termination
diff --git a/packages/playwright/src/getDescendantPids.ts b/packages/playwright/src/getDescendantPids.ts
new file mode 100644
index 0000000..25332d9
--- /dev/null
+++ b/packages/playwright/src/getDescendantPids.ts
@@ -0,0 +1,23 @@
+import { execSync } from 'node:child_process'
+
+export const getDescendantPids = (pid: number) => {
+  if (process.platform.startsWith('win')) {
+    throw new Error('getDescendantPids unsupported on Windows')
+  }
+
+  let children: number[] = []
+  try {
+    children = execSync(`pgrep -P ${pid}`, { encoding: 'utf8' }).trim().split('\n').map(Number)
+  } catch {}
+
+  const pids: number[] = []
+
+  if (children.length > 0) {
+    children.forEach((childPid) => {
+      pids.push(childPid)
+      pids.push(...getDescendantPids(childPid))
+    })
+  }
+
+  return pids
+}
diff --git a/packages/playwright/src/playwrightTestHelpers.ts b/packages/playwright/src/playwrightTestHelpers.ts
index a0892bd..8045422 100644
--- a/packages/playwright/src/playwrightTestHelpers.ts
+++ b/packages/playwright/src/playwrightTestHelpers.ts
@@ -1,9 +1,12 @@
+import type { ChildProcess } from 'node:child_process'
+
 import { test as base } from '@playwright/test'
 import { waitPort } from '@yamatomo/internal-utils'
 import { createServer } from '@yamatomo/msw-server'
 import { setupServer } from 'msw/node'
 
 import { type AppEnv, type MswParams, store } from './fixtureConfig'
+import { getDescendantPids } from './getDescendantPids.ts'
 
 const startApp = async (baseURL: string) => {
   if (!store.startApp) throw new Error('startApp is not defined.')
@@ -15,6 +18,17 @@ const startApp = async (baseURL: string) => {
   return { process, env }
 }
 
+const killAppProcess = (appProcess: ChildProcess) => {
+  if (!appProcess.pid) throw new Error('App process PID is unknown.')
+
+  getDescendantPids(appProcess.pid)
+    .reverse()
+    .forEach((pid) => {
+      process.kill(pid)
+    })
+  appProcess.kill('SIGTERM')
+}
+
 const startMswServer = async (appEnv: AppEnv) => {
   if (!store.resolveMswParams) throw new Error('resolveMswParams is not defined.')
 
@@ -37,13 +51,9 @@ const test = base.extend<TestFixtureType, WorkerFixtureType>({
 
       const app = await startApp(baseURL)
 
-      process.on('exit', () => {
-        app.process.kill('SIGINT')
-      })
-
       await use(app)
 
-      app.process.kill('SIGINT')
+      killAppProcess(app.process)
     },
     { scope: 'worker' },
   ],