てもいい | Asking Permission in Japanese

What is てもいい?

てもいい is how you ask for permission, grant permission, or deny it in Japanese. "May I sit here?" "Can I borrow this?" "You can't smoke in here." All of these situations use patterns built on the て form.

Our lesson on polite requests and permission covers these patterns alongside てください and other request forms. Here we'll break down the grammar in detail.

Asking Permission: てもいいですか？

Take the て form of the verb, add もいいですか:

The literal meaning is something like "even if I do ~, is it good?" which naturally becomes "May I ~?"

Giving Permission: てもいいです

Drop the か and you're giving permission:

• 食(た)べてもいいですよ。
  You may eat (it). / It's OK to eat.
• 帰(かえ)ってもいいです。
  You may go home.

Denying Permission: てはいけません

This is the "you must not" pattern. Replace もいい with はいけません:

てはいけません is firm -- it's a rule or strong prohibition. Think "you must not" rather than a soft "please don't" (that's more ないでください territory). The は in てはいけません is read わ, not は.

This is different from the negative imperative (するな), which is a blunt command. てはいけません states a rule; するな barks an order.

Casual Versions

In everyday conversation, these get shortened:

The casual prohibition works like this: てはだめ contracts to ちゃだめ (after て), and ではだめ contracts to じゃだめ (after で):

• 食(た)べてはだめ → 食(た)べちゃだめ (you can't eat that)
• 飲(の)んではだめ → 飲(の)んじゃだめ (you can't drink that)

Answering Permission Questions

When someone asks てもいいですか, you can respond:

The indirect refusal (ちょっと...) is very common. Japanese speakers often soften a "no" rather than saying it outright.