diff --git a/docs/syntax.md b/docs/syntax.md
index 15b7a419..9962bb74 100644
--- a/docs/syntax.md
+++ b/docs/syntax.md
@@ -182,6 +182,36 @@ each let v, arr{ // Syntax Error
 }
 ```
 
+### while
+条件がtrueの間ループを続けます。  
+条件が最初からfalseの場合はループは実行されません。
+```js
+var count = 0
+while count < 42 {
+	count += 1
+}
+<: count // 42
+// 条件が最初からfalseの場合
+while false {
+  <: 'hoge'
+} // no output
+```
+
+### do-while
+条件がtrueの間ループを続けます。  
+条件が最初からfalseであってもループは一度実行されます。
+```js
+var count = 0
+do {
+	count += 1
+} while count < 42
+<: count // 42
+// 条件が最初からfalseの場合
+do {
+  <: 'hoge'
+} while false // hoge
+```
+
 ### loop
 `break`されるまで無制限にループを行います。  
 ```js
diff --git a/src/parser/plugins/validate-keyword.ts b/src/parser/plugins/validate-keyword.ts
index a179aba7..97b1a3cf 100644
--- a/src/parser/plugins/validate-keyword.ts
+++ b/src/parser/plugins/validate-keyword.ts
@@ -19,7 +19,6 @@ const reservedWord = [
 	'constructor',
 	// 'def',
 	'dictionary',
-	'do',
 	'enum',
 	'export',
 	'finally',
@@ -44,7 +43,6 @@ const reservedWord = [
 	'use',
 	'using',
 	'when',
-	'while',
 	'yield',
 	'import',
 	'is',
diff --git a/src/parser/scanner.ts b/src/parser/scanner.ts
index 3b3aa6cd..1bba9fa7 100644
--- a/src/parser/scanner.ts
+++ b/src/parser/scanner.ts
@@ -367,6 +367,12 @@ export class Scanner implements ITokenStream {
 			case 'loop': {
 				return TOKEN(TokenKind.LoopKeyword, loc, { hasLeftSpacing });
 			}
+			case 'do': {
+				return TOKEN(TokenKind.DoKeyword, loc, { hasLeftSpacing });
+			}
+			case 'while': {
+				return TOKEN(TokenKind.WhileKeyword, loc, { hasLeftSpacing });
+			}
 			case 'break': {
 				return TOKEN(TokenKind.BreakKeyword, loc, { hasLeftSpacing });
 			}
diff --git a/src/parser/syntaxes/statements.ts b/src/parser/syntaxes/statements.ts
index 717ad579..d60b8d5b 100644
--- a/src/parser/syntaxes/statements.ts
+++ b/src/parser/syntaxes/statements.ts
@@ -45,6 +45,12 @@ export function parseStatement(s: ITokenStream): Ast.Node {
 		case TokenKind.LoopKeyword: {
 			return parseLoop(s);
 		}
+		case TokenKind.DoKeyword: {
+			return parseDoWhile(s);
+		}
+		case TokenKind.WhileKeyword: {
+			return parseWhile(s);
+		}
 		case TokenKind.BreakKeyword: {
 			s.next();
 			return NODE('break', {}, loc);
@@ -376,6 +382,54 @@ function parseLoop(s: ITokenStream): Ast.Node {
 	return NODE('loop', { statements }, loc);
 }
 
+/**
+ * ```abnf
+ * Loop = "do" BlockOrStatement "while" Expr
+ * ```
+*/
+function parseDoWhile(s: ITokenStream): Ast.Node {
+	const doLoc = s.token.loc;
+	s.nextWith(TokenKind.DoKeyword);
+	const body = parseBlockOrStatement(s);
+	const whileLoc = s.token.loc;
+	s.nextWith(TokenKind.WhileKeyword);
+	const cond = parseExpr(s, false);
+
+	return NODE('loop', {
+		statements: [
+			body,
+			NODE('if', {
+				cond: NODE('not', { expr: cond }, whileLoc),
+				then: NODE('break', {}, whileLoc),
+				elseif: [],
+			}, whileLoc),
+		],
+	}, doLoc);
+}
+
+/**
+ * ```abnf
+ * Loop = "while" Expr BlockOrStatement
+ * ```
+*/
+function parseWhile(s: ITokenStream): Ast.Node {
+	const loc = s.token.loc;
+	s.nextWith(TokenKind.WhileKeyword);
+	const cond = parseExpr(s, false);
+	const body = parseBlockOrStatement(s);
+
+	return NODE('loop', {
+		statements: [
+			NODE('if', {
+				cond: NODE('not', { expr: cond }, loc),
+				then: NODE('break', {}, loc),
+				elseif: [],
+			}, loc),
+			body,
+		],
+	}, loc);
+}
+
 /**
  * ```abnf
  * Assign = Expr ("=" / "+=" / "-=") Expr
diff --git a/src/parser/token.ts b/src/parser/token.ts
index 67aca6b6..c07030c7 100644
--- a/src/parser/token.ts
+++ b/src/parser/token.ts
@@ -19,6 +19,8 @@ export enum TokenKind {
 	EachKeyword,
 	ForKeyword,
 	LoopKeyword,
+	DoKeyword,
+	WhileKeyword,
 	BreakKeyword,
 	ContinueKeyword,
 	MatchKeyword,
diff --git a/test/keywords.ts b/test/keywords.ts
index 79848c5f..88f183a1 100644
--- a/test/keywords.ts
+++ b/test/keywords.ts
@@ -9,6 +9,8 @@ const reservedWords = [
 	'false',
 	'each',
 	'for',
+	'do',
+	'while',
 	'loop',
 	'break',
 	'continue',
diff --git a/test/syntax.ts b/test/syntax.ts
index eefb8b15..d092591c 100644
--- a/test/syntax.ts
+++ b/test/syntax.ts
@@ -758,6 +758,50 @@ describe('each', () => {
 	});
 });
 
+describe('while', () => {
+	test.concurrent('Basic', async () => {
+		const res = await exe(`
+		var count = 0
+		while count < 42 {
+			count += 1
+		}
+		<: count
+		`);
+		eq(res, NUM(42));
+	});
+
+	test.concurrent('start false', async () => {
+		const res = await exe(`
+		while false {
+			<: 'hoge'
+		}
+		`);
+		eq(res, NULL);
+	});
+});
+
+describe('do-while', () => {
+	test.concurrent('Basic', async () => {
+		const res = await exe(`
+		var count = 0
+		do {
+			count += 1
+		} while count < 42
+		<: count
+		`);
+		eq(res, NUM(42));
+	});
+
+	test.concurrent('start false', async () => {
+		const res = await exe(`
+		do {
+			<: 'hoge'
+		} while false
+		`);
+		eq(res, STR('hoge'));
+	});
+});
+
 describe('loop', () => {
 	test.concurrent('Basic', async () => {
 		const res = await exe(`
diff --git a/unreleased/while.md b/unreleased/while.md
new file mode 100644
index 00000000..c49dc5c1
--- /dev/null
+++ b/unreleased/while.md
@@ -0,0 +1 @@
+- while文とdo-while文を追加