～てもいい
Meaning
Gives permission or indicates that an action is acceptable.
"You may do..." / "It's okay if you..."
In the negative version, it means "don’t have to...", not "must not".
How to Form
| Type | Rule | Example |
|---|---|---|
| Verb | て-form + もいい | 行ってもいい → You may go |
| Negative verb | なくて + もいい | 食べなくてもいい → You don’t have to eat |
Examples
-
写真を撮ってもいいですか？
May I take a photo? -
トイレに行ってもいいです。
You may go to the bathroom. -
宿題はしなくてもいいです。
You don’t have to do the homework.
Notes
- Often used to ask or give permission politely.
- Do not confuse with 〜てはいけない, which means “must not”.
- The negative form means "not necessary", not "not allowed".
- Common in classroom and daily settings:
行ってもいいですか, 使ってもいい, 休まなくてもいい