Kotomora
JLPT N5Construction
Furigana

てはいけないMust not; may not

てはいけない says that an action is not allowed. It is a common general-purpose form for rules, warnings, and situation-specific prohibitions.

What it says

Put the action that is forbidden in the verb’s te-form, then add はいけない. The sentence presents the action as against a rule, unsafe, or otherwise not permitted; it does not mean that the action is physically impossible.

Rules and warnings

The source of the prohibition may be a public rule, a safety concern, or an instruction from someone responsible for the situation.

この展てん示じ室しつでは、フラッシュを使つかってはいけません。

You must not use flash in this exhibition room.

Analyze

The polite ending is suitable for a public rule addressed to visitors.

危あぶないから、その線せんを越こえてはいけないよ。

Don't cross that line; it's dangerous.

Analyze

This works naturally as an adult’s immediate safety warning to a child.

検けん査さの前まえは、水みずを飲のんではいけません。

You must not drink water before the examination.

Analyze

Because the verb’s te-form ends in で, adding は produces the visible sequence では.

Describing an old rule

この寮りょうでは、以い前ぜんは夜よる十じゅう一いち時じ以い降こうに外がい出しゅつしてはいけなかった。

At this dorm, going out after 11 p.m. used to be prohibited.

Analyze

The past ending describes a prohibition that applied in the past.

More examples

図と書しょ館かんでは、大おおきな声こえで話はなしてはいけません。

You must not speak loudly in the library.

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危あぶないから、ここで遊あそんではいけないよ。

Don't play here; it's dangerous.

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このパソコンに水みずをかけてはいけません。

You must not get water on this computer.

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試し験けん中ちゅうは辞じ書しょを使つかってはいけません。

You may not use a dictionary during the exam.

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当とう時じ、学がく生せいは夜よる十じゅう時じ以い降こうに外がい出しゅつしてはいけなかった。

At that time, students were not allowed to go out after 10 p.m.

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この薬くすりを飲のんだ後あとは、車くるまを運うん転てんしてはいけません。

You must not drive after taking this medicine.

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