Translation guide
Expressing prohibition: that an action is not allowed, forbidden, or must be avoided.
To state that something is strictly forbidden or not permitted, often in formal rules or strong commands.
Standard way to say 'must not do'. Used in rules, instructions, and spoken commands. The verb is in て-form.
ここでタバコを吸ってはいけません。
You must not smoke here.
この部屋に入ってはいけない。
You must not enter this room.
More formal and written than てはいけない. Often used in official rules, laws, or serious prohibitions.
この書類を外部に持ち出してはならない。
You must not take these documents outside.
Archaic/literary form meaning 'must not'. Seen on old signs or in formal writing. Not used in modern speech.
立ち入るべからず。
Do not enter.
To express that one should not do something because it is morally wrong, against one's conscience, or socially unacceptable.
Also used for personal moral prohibitions, often with こと or ものだ for general principles.
嘘をついてはいけない。
You must not lie.
約束を破ってはいけないことだ。
One must not break promises.
Expresses 'should not' based on moral or social norms. Softer than てはいけない, more about advisability.
人を傷つけるべきではない。
You should not hurt people.
Used for general moral or common-sense prohibitions: 'it is not the thing to do'. Often in proverbs or advice.
人の悪口を言うものではない。
You must not speak ill of others.
To tell someone not to do something in informal, everyday conversation.
Casual contraction of てはいけない. ちゃ after consonant-stem verbs, じゃ after vowel-stem verbs. Often used with だめ (no good).
そんなことしちゃだめだよ。
You mustn't do that.
ここで遊んじゃだめ。
You mustn't play here.
Direct negative imperative: 'Don't do!'. Very blunt, used by men or in urgent situations. Attach to dictionary form.
Soft request not to do something. Often used with ください for politeness, or alone casually.
泣かないで。
Don't cry.
ここに座らないでください。
Please don't sit here.
To express prohibition in official notices, manuals, or polite instructions.
Polite request not to do something. Standard for public signs and polite speech.
写真を撮らないでください。
Please do not take photos.
Formal way to say 'you cannot do' (it is not possible/permitted). Used in rules and customer service.
こちらでお待ちいただくことはできません。
You cannot wait here.
Noun suffix meaning 'prohibition of V'. Used on signs: 駐車禁止 (No Parking).
飲食禁止。
Eating and drinking prohibited.
てはいけない is a direct prohibition (must not), while べきではない is a moral/social advisability (should not). The former is stronger and often used for rules; the latter is softer and used for advice.
ここで走ってはいけない。
You must not run here. (rule)
人に迷惑をかけるべきではない。
You should not cause trouble for others. (moral advice)
English 'must not' is prohibition, but 'don't have to' is lack of obligation. In Japanese, なくてはいけない means 'must do', not 'must not do'. Be careful with double negatives.
行かなくてはいけない。
I must go. (not 'must not go')