Translation guide
A guide to expressing 'should not' in Japanese, covering negative obligation, prohibition, and advisability.
Expressing that something is not allowed, not right, or must not be done.
A common pattern meaning 'must not do' or 'should not do'. Used in rules, warnings, and personal advice. The verb is in て-form.
You must not smoke here.
Expressing that something is unlikely or not expected to happen.
Indicates strong conviction that something cannot or should not be the case. Attaches to the plain form.
He would never do such a thing. (He should not do such a thing.)
てはいけない is a general prohibition or rule, while べきではない expresses a moral or logical 'should not'. てはいけない is more common in everyday speech.
You must not run here. (rule)
そんなことを言ってはいけないよ。
You shouldn't say things like that.
A more casual and direct way to say 'must not do'. Often used in spoken Japanese.
You shouldn't be late.
A more formal pattern meaning 'should not do', based on moral or logical grounds. Attaches to the dictionary form of the verb.
People should not lie.
Literally 'it's better not to do', this is a softer way to advise against something. Attaches to the negative plain form.
You shouldn't go out today.
A blunt, informal prohibition used in strong commands or warnings. Attaches to the dictionary form. Mostly used by men or in rough speech.
Don't touch!
Similar to はずがない, but slightly more logical or emphatic. 'There's no reason that...'
It can't be that easy. (It shouldn't be that easy.)
One should not break promises. (moral)
There is no single Japanese word for 'should not'. Avoid translating directly as すべきではない in all cases; it can sound overly formal or moralistic. Use てはいけない for everyday prohibitions.