JLPT N4 grammar
〜てはいけない — Meaning & Examples
"Must not." て-form + はいけない. 吸ってはいけません (suttewa ikemasen) = must not smoke. Casual: 〜ちゃだめ / 〜じゃだめ.
〜てはいけない — "Must Not" (Prohibition)
〜てはいけない expresses prohibition — "you must not do ~."
Form: て-form + はいけない / はいけません
ここでたばこを吸ってはいけません。(koko de tabako o suttewa ikemasen.)
= You must not smoke here.
この写真を見てはいけません。(kono shashin o mitewa ikemasen.)
= You must not look at this photo.
Casual: 〜ては → 〜ちゃ / 〜では → 〜じゃ, often + だめ
入っちゃだめ。(haitcha dame.) = Don't go in.
食べちゃだめ。(tabecha dame.) = Don't eat that.
🎯 The full toolkit — four patterns:
・〜なければならない = must do
・〜なくてもいい = don't have to
・〜てもいい = may / allowed to
・〜てはいけない = must not
With these four, you can handle rules, permissions, and prohibitions in any situation. よくできました！(yoku dekimashita!)
Practice questions
Try these 3 questions on 〜てはいけない. Pick an answer in your head, then open “Show answer”.
1. "You don't have to come tomorrow" uses?
- 来なくてもいい (konakutemo ii)
- 来てはいけない (kite wa ikenai)
- 来なければならない (konakereba naranai)
- 来てもいい (kitemo ii)
Show answer
Answer: 来なくてもいい (konakutemo ii)
〜なくてもいい = don't have to. 明日は来なくてもいいです = you don't have to come tomorrow.
2. "You must not smoke here" uses?
- 吸わなくてもいい (suwanakutemo ii)
- 吸ってもいい (suttemo ii)
- 吸わなければならない (suwanakereba naranai)
- 吸ってはいけない (suttewa ikenai)
Show answer
Answer: 吸ってはいけない (suttewa ikenai)
〜てはいけない = must not (prohibition). ここでたばこを吸ってはいけません.
3. Casual 〜てはいけない often becomes?
- 〜てもいい (~temo ii)
- 〜なきゃ (~nakya)
- 〜ちゃだめ / 〜じゃだめ (~cha dame)
- 〜たら (~tara)
Show answer
Answer: 〜ちゃだめ / 〜じゃだめ (~cha dame)
ては→ちゃ、では→じゃ、often + だめ: 入っちゃだめ = don't go in.
Practise 〜てはいけない in the free app
This point is part of the “Must, May & Must Not — Obligation & Permission” lesson in A Star Japanese. Study it with examples, a quiz, flashcards and timed JLPT N4 mock exams. Free on iPhone and Android.
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Related N4 grammar points
From the same lesson: Must, May & Must Not — Obligation & Permission
Frequently asked questions
What does 〜てはいけない mean?
"Must not." て-form + はいけない. 吸ってはいけません (suttewa ikemasen) = must not smoke. Casual: 〜ちゃだめ / 〜じゃだめ.
Is 〜てはいけない on the JLPT N4 test?
〜てはいけない is taught in the JLPT N4 grammar course in A Star Japanese (lesson “Must, May & Must Not — Obligation & Permission”), so it is a pattern learners at this level are expected to recognise. The JLPT does not publish an official grammar list, so treat this as a study guide rather than an official requirement.
How can I practise 〜てはいけない?
Open the “Must, May & Must Not — Obligation & Permission” lesson in the free A Star Japanese app for iPhone and Android. It has examples, a quiz after every lesson, flashcards with spaced repetition and timed JLPT N4 mock exams, with no ads.