Asking for Permission: 〜てもいい
To ask 'May I...?' or 'Is it okay if I...?', Japanese uses the ~te mo ii form. It literally translates to 'Even if I do this, is it good?'
How to Ask and Give Permission
In English, we say 'May I open the window?' or 'You may sit here'. In Japanese, we attach 'mo ii' (also good) to the Te-form of the verb.
If you make it a question (〜てもいいですか？), you are asking for permission.
If you state it as a fact (〜てもいいです), you are giving permission to someone else.
You can also use this with the negative form (〜なくてもいい) to say 'You don't have to...'.
Conjugation Rules
Example Sentences
Teacher's Advice
If someone asks 'Tabete mo ii desu ka?' (May I eat?), how do you say no? Saying 'Iie, tabete mo ii ja arimasen' is WRONG! To deny permission, you must use the 'must not' grammar: '~te wa ikemasen'. So say: 'Iie, tabete wa ikemasen' (No, you must not eat).
JLPT Exam Patterns
- •Choosing the correct response to a ~te mo ii question in listening sections (N5)
- •The opposite of ~te mo ii (You may) is ~te wa ikemasen (You must not) (N5)
- •Understanding ~nakutemo ii (You don't have to) (N5)
Softening the Question
入ってもいいですか is grammatically complete and perfectly polite, but native speakers often soften it further with けど or か before finishing the thought: 入ってもいいですか、けど... trails off rather than sounding demanding. In more casual settings among peers, 入ってもいい? (dropping ですか entirely, with rising intonation) is far more common than the textbook full form.
Answering also has its own etiquette. A flat いいです can sound curt. Native speakers usually soften a 'yes' with どうぞ (please, go ahead) and soften a 'no' by avoiding a direct refusal altogether. ちょっと... (a bit...) trailing off is a very common way to decline without saying だめ or いけません outright.
Frequently Asked Questions
What does 〜てもいい mean?
〜てもいい literally means "even if you do X, it is good", or in practice, "you may / it's okay to." As a question (〜てもいいですか), it asks for permission: 入ってもいいですか ("May I come in?"). It attaches to the te-form of the verb.
How do you say something is NOT allowed in Japanese?
The negative answer to 〜てもいいですか is not 〜てもいいじゃない. Use 〜てはいけません ("you must not") or the softer 〜ないでください ("please don't"). For example: ここでタバコを吸ってはいけません.
What is the difference between 〜てもいい and 〜なくてもいい?
〜てもいい gives permission to do something, while 〜なくてもいい says something is not necessary: 行かなくてもいい means "you don't have to go." The JLPT often tests this pair together, so learn them as a set.
Related Grammar
Master Permissions
Practice asking for and giving permission in various situations.