What is 〜てはだめ?
〜てはだめ is a casual way to express prohibition, meaning "must not," "can't," or "don't." It's softer and more colloquial than てはいけない.
食べてはだめ
"You can't eat" / "Don't eat"
行ってはだめだよ
"You mustn't go"
Formation
Pattern: Verb て-form + は + だめ(です)
| Verb | て-form | + はだめ |
|---|---|---|
| 食べる | 食べて | 食べてはだめ |
| 行く | 行って | 行ってはだめ |
| 見る | 見て | 見てはだめ |
| する | して | してはだめ |
Contraction: 〜ちゃだめ
Common in casual speech:
食べてはだめ → 食べちゃだめ
行ってはだめ → 行っちゃだめ
してはだめ → しちゃだめ
見てはだめ → 見ちゃだめ
だめ vs いけない
| Feature | だめ | いけない |
|---|---|---|
| Formality | Casual | More formal |
| Tone | Friendlier | Stricter |
| Usage | Daily conversation | Rules, formal |
Casual: 食べちゃだめ
Formal: 食べてはいけません
Both mean: "You mustn't eat"
Basic Usage
Giving warnings/advice
それ触っちゃだめ！
"Don't touch that!"
一人で行ってはだめだよ
"You mustn't go alone"
そんなこと言っちゃだめ
"You can't say such things"
Parental/friendly prohibition
危ないからだめ！
"No, because it's dangerous!"
まだ食べちゃだめ
"You can't eat yet"
遅くまで起きてちゃだめ
"You shouldn't stay up late"
Politeness Levels
Very Casual
食べちゃだめ
"Don't eat"
行っちゃだめ
"Don't go"
見ちゃだめ
"Don't look"
Casual Polite
食べてはだめです
"You can't eat" (polite but casual)
行ってはだめですよ
"You mustn't go"
Explanation with だめ
だめなんです
"It's not allowed"
だめなの
"You can't" (explaining)
Common Conversations
Example 1: Parent and Child
A: ママ、これ食べてもいい？
"Mom, can I eat this?"
B: だめだめ、まだ夕飯前よ
"No no, it's still before dinner"
A: えー、少しだけ？
"Aww, just a little?"
B: だめって言ってるでしょ
"I said no, didn't I"
Example 2: Between Friends
A: 一人で行ってくるね
"I'll go alone"
B: ちょっと待って！一人で行っちゃだめだよ
"Wait! You can't go alone"
A: 大丈夫だって
"It'll be fine"
B: だめだって。一緒に行くから
"No way. I'll go with you"
Example 3: At Home
A: ゲームしてもいい？
"Can I play games?"
B: 宿題終わった？
"Did you finish homework?"
A: まだ...
"Not yet..."
B: じゃあだめ。宿題が先
"Then no. Homework first"
Using だめ Alone
Just "だめ" as response
A: これ使ってもいい？
"Can I use this?"
B: だめ
"No" / "You can't"
A: 明日は？
"How about tomorrow?"
B: 明日もだめ
"Tomorrow's no good either"
Softening the Prohibition
Adding particles for softer tone
食べちゃだめだよ
"You can't eat (I'm telling you)"
行っちゃだめだからね
"You can't go, okay?"
触っちゃだめって言ったでしょ
"I told you not to touch it, right?"
Common Expressions
だめだよ / だめだ
それはだめだよ
"That's no good"
絶対だめだ
"Absolutely not"
どうしてもだめ？
"Is it really not possible?"
だめなの
Explanation form:
なんでだめなの？
"Why not?" / "Why can't I?"
今はだめなの
"Not now" / "You can't right now"
Reasons with から
Explaining why it's だめ
危ないからだめ
"No, because it's dangerous"
まだ早いからだめ
"No, because it's still early"
お金がないからだめ
"No, because there's no money"
Comparison with Other Forms
てはだめ (casual prohibition)
食べちゃだめ
"Don't eat" (casual, friendly)
てはいけない (formal prohibition)
食べてはいけません
"You must not eat" (formal, strict)
ないでください (polite request)
食べないでください
"Please don't eat" (polite request)
ないほうがいい (advice)
食べないほうがいい
"It's better not to eat" (advice)
Common Mistakes
Mistake 1: Using in formal situations
Wrong context: 上司に「それはだめです」 ⚠️
Better: 「申し訳ございませんが...」 ✓
"I'm sorry but..."
だめ is too casual for superiors!
Mistake 2: Wrong conjugation
Wrong: 食べるはだめ ❌
Right: 食べてはだめ ✓
"You can't eat"
Must use て-form!
Mistake 3: Confusing with できない
だめ = not allowed (prohibition)
できない = cannot (ability)
食べちゃだめ = "You can't eat" (not allowed)
食べられない = "I can't eat" (unable to)
Expressing Strong Prohibition
絶対だめ (absolutely not)
絶対に触っちゃだめ！
"You absolutely must not touch!"
絶対だめだからね
"It's absolutely not allowed, okay?"
With Conditional
〜たらだめ (if you do, it's bad)
遅刻したらだめだよ
"You can't be late" (If you're late, it's bad)
忘れたらだめ
"Don't forget" (If you forget, it's bad)
Various Uses of だめ
As adjective (no good)
この案はだめだ
"This plan is no good"
もうだめだ
"It's hopeless / I'm done for"
As permission denial
A: いい？
"Is it okay?"
B: だめ
"No"
As impossibility
もう歩けない。だめだ
"I can't walk anymore. I'm done"
Repeated だめ for Emphasis
だめだめだめ！
"No, no, no!"
だめったらだめ！
"I said no!"
Written Style
In writing, だめ is usually written in hiragana:
Hiragana: だめ (common)
Kanji: 駄目 (less common)
Katakana: ダメ (emphasis/casual)
Explaining Rules
Using だめ to state rules
ここは禁煙だから、吸っちゃだめ
"This is non-smoking, so you can't smoke"
まだ子供だから、見ちゃだめ
"You're still a child, so you can't watch"
Question Form
〜てはだめですか？
食べてはだめですか？
"Can't I eat?" / "Is eating not allowed?"
行っちゃだめ？
"Can't I go?"
Practice Sentences
Basic
それ触っちゃだめ
"Don't touch that"
ここで遊んじゃだめ
"You can't play here"
嘘をついちゃだめだよ
"You mustn't lie"
Intermediate
まだ宿題終わってないでしょ？ゲームしちゃだめ
"You haven't finished homework yet, right? You can't play games"
一人で夜道を歩いちゃだめだよ
"You can't walk alone on night streets"
そんなに食べちゃだめ。お腹壊すよ
"Don't eat so much. You'll get a stomachache"
Advanced
危ないから絶対に近づいちゃだめだからね
"It's dangerous, so absolutely don't go near it, okay?"
この秘密は誰にも言っちゃだめだよ。約束して
"You can't tell this secret to anyone. Promise"
諦めちゃだめ！まだチャンスはあるから
"Don't give up! There's still a chance"
Related Grammar Points
- 〜てはいけない - Must not (formal)
- 〜ないでください - Please don't
- 〜てもいい - May/Permission
- 〜ないほうがいい - Better not to
- て-form - Te-form conjugation
- Prohibition expressions - Various prohibition forms