N5#te-form#prohibition#grammar#verbs

〜てはいけない (Prohibition)

Learn how to express that an action is prohibited or not allowed.

Context

Rules and Restrictions

In daily life, you often encounter situations where certain actions are forbidden. Whether it is a sign in a library, a rule at school, or a parent telling a child not to do something, you need a way to express that an action is not permitted.

Imagine you are visiting a museum. You see a sign that tells you not to touch the art. How do you say that in Japanese? Or perhaps you are in a park and want to tell someone they cannot walk on the grass. The grammar point 〜てはいけない is the standard way to express these prohibitions.

Explanation

How to form Prohibition

To express that an action is forbidden, you take the te-form of a verb and add は (wa) and いけない (ikenai).

Verb-te formはいけない

The te-form acts as the base for the action, and the particle は emphasizes the restriction. The word いけない literally means 'cannot go' or 'is not acceptable.' When combined, it creates a firm statement that an action is not allowed.

Tip

Remember that the te-form conjugation depends on the verb group (u-verbs, ru-verbs, or irregular verbs). Ensure your te-form is correct before adding は + いけない.

Examples

Examples of Prohibition

Here are some common ways to use this structure in daily life.

ここで写真(しゃしん)を撮って(とって)はいけません。

You must not take photos here.

ここここhereででat写真しゃしんphotoををobject marker撮ってとってtake (te-form)はいけませんはいけませんmust not

芝生(しばふ)に入って(はいって)はいけない。

Do not enter the grass.

芝生しばふgrass/lawnににinto入ってはいってenter (te-form)はいけないはいけないmust not

ここにゴミを【すてて】はいけません。

Hint: The verb is すてる (to throw away).

You must not throw trash here.

Usage

Nuance and Register

The phrase 〜てはいけない is quite direct and authoritative. It is often used by people in positions of authority (like teachers or parents) or on formal signs.

〜てはいけません

Polite form, used in public or to strangers.

入ってはいけません。

〜てはいけない

Plain form, used in writing or by authority figures.

入ってはいけない。

Which version is more appropriate when speaking to a stranger in a polite setting?

〜てはいけない
✓ 〜てはいけません

〜てはいけません is the polite form (masu-form), making it suitable for polite conversation.

Deep dive

Deep Dive: Variations

Sometimes you will hear variations of this grammar point in spoken Japanese.

Common variations

In casual speech, people often contract 〜てはいけない to 〜ちゃいけない (cha-ikenai). For verbs ending in 'de' (like 読んで), it becomes 〜じゃいけない (ja-ikenai). These are very informal and should be avoided in professional or polite settings.

Summary

You have learned how to use the te-form + は + いけない to express prohibition. Remember to adjust the politeness level based on who you are speaking to.

撮る

とるverb

to take (a photo)

入る

はいるverb

to enter

捨てる

すてるverb

to throw away

芝生

しばふnoun

lawn/grass

写真

しゃしんnoun

photo