てはいけない — The Absolute Wall
Declares an action forbidden — legally, morally, or by the rules. It literally reads "as for doing X, it won't do". This is a stronger, more authoritative prohibition than a simple negative request.
Structure
[Verb te-form] + はいけない / はいけません
Examples
ここで写真を撮ってはいけません。
Koko de shashin o totte wa ikemasen.
You must not take pictures here.
撮って (take, te-form) + は (topic marker) + いけません (won't do / not allowed)
絶対に入ってはいけない。
Zettai ni haitte wa ikenai.
You absolutely must not enter.
絶対に (absolutely) + 入って (enter) + はいけない (plain, stern prohibition)
そんなことをしてはいけないよ。
Sonna koto o shite wa ikenai yo.
You shouldn't do that kind of thing.
そんなこと (such a thing) + して (do) + はいけないよ (authoritative scolding, よ for emphasis)
• The ladder of prohibition: 1) てはいけません (public signs / teachers — stern authority). 2) てはだめです (common scolding — firm but personal). 3) ちゃだめ！ (casual contraction — ては collapses into ちゃ). • This is NOT a polite request. To ask someone nicely not to do something, use 〜ないでください instead.
Commonly confused with
The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones てはいけない is tested against.
vs 〜ないでください
ないでください is a polite request not to do something ('please don't'); てはいけない is a firm rule or prohibition ('you must not').
vs 〜なければならない
なければならない states a positive obligation ('must do'); てはいけない states the opposite — a ban on doing ('must not do').
vs 〜なくてもいい
なくてもいい gives permission to NOT do something ('you don't have to'); てはいけない removes permission to do it at all.
Study Japanese grammar on LenGaki
Everything on this page, free to browse
- 7,788 JLPT vocabulary words, N5 through N1, with readings and audio
- 2,057 kanji with on'yomi, kun'yomi and stroke-order practice
- 444 grammar points with examples and commonly-confused comparisons
- Full-length N5 and N4 mock exams, timed, with real listening audio
Get the Android app