diff --git a/packages/frontend-shared/build.js b/packages/frontend-shared/build.js
index 17b6da8d3..994111475 100644
--- a/packages/frontend-shared/build.js
+++ b/packages/frontend-shared/build.js
@@ -23,10 +23,14 @@ const options = {
 	sourcemap: 'linked',
 };
 
-// js-built配下をすべて削除する
-fs.rmSync('./js-built', { recursive: true, force: true });
+const args = process.argv.slice(2).map(arg => arg.toLowerCase());
 
-if (process.argv.map(arg => arg.toLowerCase()).includes('--watch')) {
+// js-built配下をすべて削除する
+if (!args.includes('--no-clean')) {
+	fs.rmSync('./js-built', { recursive: true, force: true });
+}
+
+if (args.includes('--watch')) {
 	await watchSrc();
 } else {
 	await buildSrc();
diff --git a/packages/misskey-bubble-game/build.js b/packages/misskey-bubble-game/build.js
index a80b71646..5d534cc6f 100644
--- a/packages/misskey-bubble-game/build.js
+++ b/packages/misskey-bubble-game/build.js
@@ -23,10 +23,14 @@ const options = {
 	sourcemap: 'linked',
 };
 
-// built配下をすべて削除する
-fs.rmSync('./built', { recursive: true, force: true });
+const args = process.argv.slice(2).map(arg => arg.toLowerCase());
 
-if (process.argv.map(arg => arg.toLowerCase()).includes('--watch')) {
+// built配下をすべて削除する
+if (!args.includes('--no-clean')) {
+	fs.rmSync('./built', { recursive: true, force: true });
+}
+
+if (args.includes('--watch')) {
 	await watchSrc();
 } else {
 	await buildSrc();
diff --git a/packages/misskey-js/build.js b/packages/misskey-js/build.js
index a80b71646..b79459281 100644
--- a/packages/misskey-js/build.js
+++ b/packages/misskey-js/build.js
@@ -24,9 +24,14 @@ const options = {
 };
 
 // built配下をすべて削除する
-fs.rmSync('./built', { recursive: true, force: true });
+const args = process.argv.slice(2).map(arg => arg.toLowerCase());
 
-if (process.argv.map(arg => arg.toLowerCase()).includes('--watch')) {
+// built配下をすべて削除する
+if (!args.includes('--no-clean')) {
+	fs.rmSync('./built', { recursive: true, force: true });
+}
+
+if (args.includes('--watch')) {
 	await watchSrc();
 } else {
 	await buildSrc();
diff --git a/packages/misskey-reversi/build.js b/packages/misskey-reversi/build.js
index a80b71646..5d534cc6f 100644
--- a/packages/misskey-reversi/build.js
+++ b/packages/misskey-reversi/build.js
@@ -23,10 +23,14 @@ const options = {
 	sourcemap: 'linked',
 };
 
-// built配下をすべて削除する
-fs.rmSync('./built', { recursive: true, force: true });
+const args = process.argv.slice(2).map(arg => arg.toLowerCase());
 
-if (process.argv.map(arg => arg.toLowerCase()).includes('--watch')) {
+// built配下をすべて削除する
+if (!args.includes('--no-clean')) {
+	fs.rmSync('./built', { recursive: true, force: true });
+}
+
+if (args.includes('--watch')) {
 	await watchSrc();
 } else {
 	await buildSrc();
diff --git a/scripts/dev.mjs b/scripts/dev.mjs
index ede77554d..3f66028be 100644
--- a/scripts/dev.mjs
+++ b/scripts/dev.mjs
@@ -27,20 +27,7 @@ await Promise.all([
 		stdout: process.stdout,
 		stderr: process.stderr,
 	}),
-	execa('pnpm', ['--filter', 'misskey-js', 'build'], {
-		cwd: _dirname + '/../',
-		stdout: process.stdout,
-		stderr: process.stderr,
-	}),
-]);
-
-await Promise.all([
-	execa('pnpm', ['--filter', 'misskey-reversi', 'build'], {
-		cwd: _dirname + '/../',
-		stdout: process.stdout,
-		stderr: process.stderr,
-	}),
-	execa('pnpm', ['--filter', 'misskey-bubble-game', 'build'], {
+	execa('pnpm', ['--filter', 'backend...', 'build'], {
 		cwd: _dirname + '/../',
 		stdout: process.stdout,
 		stderr: process.stderr,
@@ -65,7 +52,7 @@ execa('pnpm', ['--filter', 'backend', 'dev'], {
 	stderr: process.stderr,
 });
 
-execa('pnpm', ['--filter', 'frontend-shared', 'watch'], {
+execa('pnpm', ['--filter', 'frontend-shared', 'watch', '--no-clean'], {
 	cwd: _dirname + '/../',
 	stdout: process.stdout,
 	stderr: process.stderr,
@@ -89,19 +76,19 @@ execa('pnpm', ['--filter', 'sw', 'watch'], {
 	stderr: process.stderr,
 });
 
-execa('pnpm', ['--filter', 'misskey-js', 'watch'], {
+execa('pnpm', ['--filter', 'misskey-js', 'watch', '--no-clean'], {
 	cwd: _dirname + '/../',
 	stdout: process.stdout,
 	stderr: process.stderr,
 });
 
-execa('pnpm', ['--filter', 'misskey-reversi', 'watch'], {
+execa('pnpm', ['--filter', 'misskey-reversi', 'watch', '--no-clean'], {
 	cwd: _dirname + '/../',
 	stdout: process.stdout,
 	stderr: process.stderr,
 });
 
-execa('pnpm', ['--filter', 'misskey-bubble-game', 'watch'], {
+execa('pnpm', ['--filter', 'misskey-bubble-game', 'watch', '--no-clean'], {
 	cwd: _dirname + '/../',
 	stdout: process.stdout,
 	stderr: process.stderr,