"May I take a photo?" "You can go home now." English hands permission through a modal verb — may, can — sitting in front of the action. Japanese does something more literal and, once you see it, more elegant: it says "even if you do X, it's fine." The pattern is 〜てもいい, built from the te-form plus もいい, and the little も ("even") is doing real semantic work — it frames the action as one that, even when carried out, causes no problem. That is precisely what permission is.
This page shows how to grant permission, how to ask for it politely, and how 〜てもいい mirrors prohibition so exactly that the two are the same te-form riding opposite particles. Getting the も right is what separates natural, considerate Japanese from a slightly off-key request.
Building it: te-form + もいい
Take the te-form of the verb and add もいい. That's the whole recipe.
| Verb | te-form |
|
|---|---|---|
| 座る (sit) | 座って | 座ってもいい |
| 帰る (go home) | 帰って | 帰ってもいい |
| 食べる (eat) | 食べて | 食べてもいい |
| 撮る (take a photo) | 撮って | 撮ってもいい |
| 借りる (borrow) | 借りて | 借りてもいい |
| する (do) | して | してもいい |
Granting permission: the statement
As a plain statement, 〜てもいい gives permission. Add よ to make the granting warm and clear; add です for politeness.
ここで食べてもいい。
koko de tabete mo ii
You can eat here.
もう帰ってもいいよ。お疲れさま。
mō kaette mo ii yo. otsukaresama
You can head home now. Good work today.
この資料はコピーしてもいいですよ。
kono shiryō wa kopī shite mo ii desu yo
You're welcome to make copies of these materials.
Asking permission: the question
Turn the same pattern into a question — 〜てもいいですか — and you are requesting permission. This is one of the highest-frequency polite patterns in daily Japanese: shops, offices, homes, classrooms.
写真を撮ってもいいですか。
shashin o totte mo ii desu ka
May I take a photo?
ここに座ってもいいですか。
koko ni suwatte mo ii desu ka
Is it okay if I sit here?
窓を開けてもいい？ちょっと暑くて。
mado o akete mo ii? chotto atsukute
Can I open the window? It's a bit hot. (casual)
The natural reply to such a question is not another 〜てもいい but a set phrase: ええ、どうぞ ("yes, go ahead") to grant, or a hesitant すみません、ちょっと… to decline. A flat 食べてはいけません ("you must not") as a refusal is grammatically fine but socially blunt — Japanese usually softens a "no" rather than stating the prohibition outright.
Softer, more deferential requests
When you want to be more polite — asking a superior, a stranger, or for something that might inconvenience others — upgrade the ending. Two workhorses:
- 〜てもいいでしょうか — でしょうか replaces ですか with a tentative, humble tone ("might it be all right if…").
- 〜てもかまいませんか — かまわない ("[I] don't mind") is more formal than いい; ませんか makes it a courteous question.
ペンを借りてもいいでしょうか。
pen o karite mo ii deshō ka
Might I borrow a pen? (deferential)
こちらのお席を使ってもかまいませんか。
kochira no o-seki o tsukatte mo kamaimasen ka
Would you mind if I used this seat? (formal)
As a granting reply, 〜てもかまいません ("I don't mind if you…") is a gracious way to say yes:
写真は撮ってもかまいませんが、フラッシュはご遠慮ください。
shashin wa totte mo kamaimasen ga, furasshu wa go-enryo kudasai
You're welcome to take photos, but please refrain from using flash.
The も / は symmetry: permission and prohibition are twins
Here is the structural insight worth carrying away. Permission 〜てもいい and prohibition 〜てはいけない are built on the same te-form — they differ only in the particle and the evaluation:
| Particle | Pattern | Meaning | Literal sense |
|---|---|---|---|
| も ("even") | 〜てもいい | may / it's fine to | "even doing it is good" |
| は ("as for") | 〜てはいけない | must not | "doing it — as for that — won't do" |
Swap も for は and "you may sit here" becomes "you must not sit here." That is why dropping or mis-choosing the particle is not a small slip — it can flip permission into prohibition.
ここで写真を撮ってもいいですが、あそこでは撮ってはいけません。
koko de shashin o totte mo ii desu ga, asoko de wa totte wa ikemasen
You may take photos here, but over there you must not.
Permission (てもいい) is not ability (できる)
English "can" is ambiguous — "Can I take photos?" might ask permission or physical possibility. Japanese keeps these apart. 〜てもいい asks whether an action is allowed; the potential form or できる asks whether it is possible. 写真が撮れますか literally asks "are photos able to be taken (does the camera work / is it feasible)?" — not "am I permitted?"
ここで写真を撮ってもいいですか。
koko de shashin o totte mo ii desu ka
Am I allowed to take photos here? (permission)
暗くても、写真が撮れますか。
kurakute mo, shashin ga toremasu ka
Even in the dark, can photos be taken (is it possible)? (ability)
When you want to ask a museum guard whether photography is permitted, 撮ってもいいですか is the correct choice — 撮れますか risks being heard as "is your camera capable of it?"
Beyond permission: 〜でもいい, "X is fine too"
The same もいい tail attaches to a noun to mean "even X will do / X is fine too" — not permission to act, but acceptance of an option. It is the everyday way to signal flexibility when someone is choosing or proposing.
飲み物はお茶でもいいですか。
nomimono wa o-cha de mo ii desu ka
Would tea be okay for the drink?
今日は忙しいので、打ち合わせは明日でもいいですか。
kyō wa isogashii node, uchiawase wa ashita de mo ii desu ka
I'm tied up today, so would tomorrow be okay for the meeting?
Notice this is the noun sibling of verbal permission: 撮ってもいい ("even taking a photo is fine") and お茶でもいい ("even tea is fine") run on the identical "even X → no problem" logic — one built on a te-form, the other on a noun plus で. Recognizing the shared も lets you read both at a glance.
Common mistakes
❌ 帰ってはいいですか。
kaette wa ii desu ka
Wrong particle — は here builds the prohibition frame, not permission.
✅ 帰ってもいいですか。
kaette mo ii desu ka
May I go home? (permission uses も)
❌ ここで写真が撮れますか。
koko de shashin ga toremasu ka
Off-target when you mean to ask permission — 撮れますか asks about ability/possibility, not whether it's allowed.
✅ ここで写真を撮ってもいいですか。
koko de shashin o totte mo ii desu ka
Is it okay to take photos here? (asks permission)
❌ この席を使ってもいいだ。
kono seki o tsukatte mo ii da
Incorrect — いい is already the predicate; don't add だ.
✅ この席を使ってもいい。
kono seki o tsukatte mo ii
You can use this seat.
❌ 食べいいですか。
tabe ii desu ka
Incorrect — you need the full te-form plus も: 食べてもいい, not the bare stem.
✅ 食べてもいいですか。
tabete mo ii desu ka
May I eat this?
Key takeaways
- 〜てもいい = "may / it's fine to" — te-form + もいい, literally "even if you do it, it's fine." The も ("even") frames the action as harmless-even-when-done.
- The statement grants permission; the question 〜てもいいですか asks for it. Polite/deferential upgrades: 〜てもいいでしょうか and 〜てもかまいませんか.
- Permission and prohibition are the same te-form on opposite particles: も grants ("even doing it is fine"), は forbids (〜てはいけない).
- Keep permission (てもいい, allowed?) separate from ability (できる / potential form, possible?) — English "can" blurs them, Japanese does not.
- Refusals are usually softened (すみません、ちょっと…), not stated as bald prohibitions.
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Start learning Japanese→Related Topics
- 〜てはいけない / 〜ちゃだめ: ProhibitionN4 — How Japanese forbids an action by topicalizing it with は and rejecting it — the mirror image of 〜てもいい permission, from stiff public signs (〜てはいけません) to a parent's 〜ちゃだめ.
- 〜なくてもいい: No Need ToN4 — How 〜なくてもいい grants permission NOT to do something — the exact cancellation of obligation — and why English speakers must keep it clear of 〜てはいけない ('must not').
- 〜なければならない: Obligation ('must')N4 — The core Japanese way to say something must be done — a double negative meaning 'if you don't do it, it won't do' — plus how to build it correctly from the ない-stem and how ならない, いけない, and ねばならない differ.