LESSON NOTES · レッスンノート

N4Lesson notes · Sep 30, 2026

Of course in Japanese: もちろん, 当然とうぜん, and the "of course" that sounds cold

"Of course" in Japanese is もちろん — warm, safe and almost always right. 当然とうぜん and 当たり前あたりまえ also translate as "of course," but they say "that's obvious," and depending on your tone they can sound cold or even a little superior.

English has one "of course" that stretches from "Sure, happy to!" to "Duh." Japanese splits that range across several words, and picking the wrong one is how a friendly learner ends up sounding like they are correcting the other person. This article sorts them by temperature and situation.

The basics

What is the safest way to say "of course" in Japanese?

もちろん (勿論もちろん) is the safe one. It works as a full answer by itself, and it sounds positive and confident rather than annoyed.

もちろん! — Of course! (casual, warm, a full answer on its own) もちろんです。 — Of course. (polite, safe with strangers, colleagues, shop staff) はい、もちろん。 — Yes, of course. (polite, when someone asks if you can help)

In service settings you may also hear a more formal version, もちろんでございます, but as a learner you can live happily on もちろん and もちろんです.

If you want the bigger picture of how Japanese says "yes" in general, our guide to how to say yes in Japanese covers はい, ええ and うん. もちろん is what you add when you want the yes to be enthusiastic.

How do you say "of course I will" or "of course I can"?

Put もちろん in front of the sentence. It behaves like an adverb that strengthens whatever follows.

もちろん行いくよ。 — Of course I'm going. (casual, friend to friend) もちろんお手伝てつだいします。 — Of course, I'll help. (polite, offering help)

You can also use it to answer a question about yourself. If someone asks whether you'll come, もちろん by itself already means "of course I will."

How do you say "of course not"?

Attach the negative to もちろん, or answer the question directly.

もちろん違ちがいます。 — Of course not. / Of course that's not it. (polite, calm) もちろん、怒おこってないよ。 — Of course I'm not angry. (casual, reassuring)

One small trap: if someone thanks you or apologizes and you want to say "of course, don't mention it," もちろん is not the usual reply. Japanese people typically say どういたしまして, いえいえ, or とんでもないです instead.

Beyond the basics

What is もちろん〜も, or 〜はもちろん?

This is a second job for the same word. 〜はもちろん、〜も means "not only ~, but also ~" — you treat the first item as too obvious to discuss, then add a second one.

英語えいごはもちろん、日本語にほんごも話はなせます。 — I can speak not only English but also Japanese. (polite, resume or self-introduction style) この店みせはラーメンはもちろん、餃子ぎょうざもおいしい。 — The ramen is good, of course, and the gyoza is delicious too. (casual, a recommendation)

The first half is "obviously true," and the second half is the surprise or the bonus. In this pattern もちろん is not answering anybody, so the coldness problem below does not apply.

Can もちろん also mean "admittedly"?

Yes. At the start of a sentence, もちろん can concede a point before you say "but."

もちろん高たかいけど、それだけの価値かちはあるよ。 — Sure, it's expensive, but it's worth it. (casual, conceding a point)

That is the "of course, it's true that…" use, and it is common in speech and in writing.

Then what is the difference between もちろん, 当然とうぜん and 当たり前あたりまえ?

They all say "obviously," but もちろん agrees with the other person, while 当然とうぜん and 当たり前あたりまえ comment on how obvious the thing is.

  • 当然とうぜん (とうぜん) means "naturally, as it should be." It sounds a bit stronger and more formal than もちろん. It often carries the feeling of "this follows logically" or "it's only right."
  • 当たり前あたりまえ (あたりまえ) means "obvious, a matter of course." It can also mean "ordinary, taken for granted," which is why it is a fine word in a sentence like 挨拶あいさつをするのは当たり前あたりまえです ("Greeting people is only proper").

当然とうぜんです。 — Naturally. / Of course, that's only right. (polite but firm, can sound stiff) 当然とうぜんでしょ。 — Well, obviously. (casual, a little superior — "why are you even asking?") 当たり前あたりまえでしょ。 — Obviously! (casual, can sound impatient) 当たり前あたりまえだ! — Of course! / Obviously! (blunt, strong, often anime-style shouting)

Notice the pattern: the moment you attach でしょ or じゃん to 当然とうぜん or 当たり前あたりまえ, you are no longer saying "yes," you are saying "that was a silly question." Between close friends it can be a joke. To a colleague, a teacher or a customer, it can land badly.

Why does 当然とうぜん! sound cold as a translation of "Of course!"?

Because English "Of course!" is often just a friendly yes. Translating it word by word as 当然とうぜん! gives you a Japanese sentence whose main message is "this is self-evident." Imagine someone asks "Can I borrow your pen?" and you answer 当然とうぜんでしょ. In English terms that is closer to "Well, obviously," which is not what you meant.

If you want the friendly meaning, choose もちろん, or answer with the actual content of the request. The next section shows what that looks like.

What if someone is asking a favor?

For requests, もちろん is fine, but often Japanese speakers reach for something softer that simply grants the request.

いいですよ。 — Sure, that's fine. (polite, relaxed, the よ adds reassurance) どうぞ。 — Please, go ahead. (polite, when someone asks to use or take something) もちろんいいですよ。 — Of course, that's fine. (polite, extra warm)

Here いいですよ often sounds gentler than a bare もちろん, because it does not suggest "of course, why would you even doubt it?" If the other person is asking permission, our guide to te mo ii desu ka shows the question side, and どうぞ is the answer that matches it best.

What about the written "of course"?

言いうまでもなく (いうまでもなく) means "needless to say" and belongs mostly in writing and speeches, with a formal, slightly bookish tone.

言いうまでもなく、安全あんぜんが最優先さいゆうせんです。 — Needless to say, safety comes first. (formal, written or announcement style)

It is an opener for a statement you want to present as a shared principle. You would rarely use it as a one-word reply in conversation.

Can "of course" ever be sarcastic in Japanese?

Yes, and it is the same trap in reverse. Tone and context can turn 当然とうぜん or 当たり前あたりまえ into a jab. Whether a line is sincere or ironic depends on voice, timing and relationship, which we cover in Japanese sarcasm. When in doubt, もちろん is the option least likely to be read as sarcastic.

The "of course" cheat sheet

Word Temperature Typical situation
もちろん Warm, positive Agreeing, accepting a request, everyday default
もちろんです Warm, polite Shop, work, anyone you are not close with
いいですよ Soft, easygoing Granting a favor or permission
どうぞ Soft, inviting Offering something or allowing an action
当然とうぜんです Firm, a bit stiff Explaining that something is only right or logical
当然とうぜんでしょ Cool, a bit superior Close friends, when the answer is obvious
当たり前あたりまえでしょ/当たり前あたりまえだ Blunt, can sound annoyed Strong emotion, anime-style lines, close friends
言いうまでもなく Formal, written Speeches, articles, formal statements

Common mistakes

  • Translating every "Of course!" as 当然とうぜん! When "of course" means "sure, happy to," use もちろん. 当然とうぜん tells the listener the answer was obvious.
  • Using 当たり前あたりまえでしょ with someone you don't know well. It can sound impatient. Even if the grammar is right, the effect is "you shouldn't have to ask."
  • Answering a favor request with only 当然とうぜんです. It sounds like a statement of principle. いいですよ or もちろんです is friendlier.
  • Using もちろん in reply to thanks. Use いえいえ or どういたしまして instead.
  • Forgetting that もちろん〜も is not a yes. In 英語えいごはもちろん、日本語にほんごも, もちろん introduces a bonus item, not an agreement with anybody.
  • Treating 言いうまでもなく as a chat word. It is a written-style opener.

Practice

Build each answer before opening it. Questions 3 and 4 are a pair — the same situation with two different words.

1. A colleague asks, "Can you come to the meeting tomorrow?" You want a warm, polite yes. What do you say?

Show answer

もちろんです — polite, warm and positive. It agrees without commenting on how obvious the question was.

2. Say "I can speak not only English but also Japanese" using もちろん.

Show answer

英語えいごはもちろん、日本語にほんごも話はなせます — 〜はもちろん、〜も treats the first item as obvious and adds a second one.

3. A friend asks, "Are you coming to the party?" You answer 当然とうぜんでしょ. How might it sound?

Show answer

A bit superior — 当然とうぜんでしょ carries "obviously, why ask?" With a close friend and a joking tone it can be fun, but the word itself comments on how obvious the answer is.

4. Same question, but you want it to sound friendly. What do you say instead?

Show answer

もちろん行いくよ — もちろん agrees warmly, and 行いくよ answers the actual question. This is the pair to question 3.

5. Someone asks 座すわってもいいですか and you want to grant it gently. Give one natural answer that is not 当然とうぜん.

Show answer

どうぞ/いいですよ — both grant the request without suggesting that the question was silly.

6. Which sounds like a statement of principle, もちろんです or 当然とうぜんです?

Show answer

当然とうぜんです — it means "that's only natural or right," so it explains rather than simply agrees.

7. Complete the sentence with a word meaning "needless to say": ___、安全あんぜんが最優先さいゆうせんです。

Show answer

言いうまでもなく — a formal, written-style opener for something presented as self-evident.

8. Someone thanks you for a small favor. Why is もちろん not the usual reply?

Show answer

もちろん answers questions and requests, not thanks. Use いえいえ, どういたしまして or とんでもないです.

9. Say "Of course it's expensive, but it's worth it" using もちろん as a concession.

Show answer

もちろん高たかいけど、それだけの価値かちはあります — もちろん concedes the point before the けど turns the sentence around.

10. A learner says 当然とうぜん! to mean a cheerful "Of course!" to a stranger who asked for help. What is the problem?

Show answer

It sounds like "that's obvious." The intended warmth is lost; もちろんです or いいですよ would fit.

With a teacher in a trial lesson, answer a friend's request with もちろん, then see how 当然とうぜん or 当たり前あたりまえ would sound in the same spot.

FAQ

Is もちろん ever rude? Rarely. It can sound a little emphatic if you say it flatly, but it is the standard friendly "of course." 当然とうぜん and 当たり前あたりまえ are the ones that carry the "obviously" edge.

Can I use もちろん in an email or at work? Yes. もちろんです is fine with colleagues and customers, and もちろんでございます is a very formal version you may hear from service staff.

What is the difference between 当然とうぜん and 当たり前あたりまえ? Both mean "obvious," and in many sentences they are interchangeable. 当たり前あたりまえ also has the sense of "ordinary, taken for granted," while 当然とうぜん leans toward "logical, as it should be." Either can sound blunt when used as a reply with でしょ.

Can I answer a yes/no question with just もちろん? Yes. もちろん is a complete answer. For "of course not," say もちろん違ちがいます or もちろんそんなことないよ, since もちろん alone is read as "yes."

Is 言いうまでもなく used in conversation? Not much. It sounds like writing or a speech. In conversation, people usually say もちろん or 当然とうぜん instead.

Vocabulary from this article

Tap the block to select all of it, then copy. In Anki: File → Import, note type Basic, separator Tab — the first column becomes the front, the second the back.

もちろん	もちろん — of course
当然	とうぜん — naturally, as it should be
当たり前	あたりまえ — obvious, taken for granted
言うまでもなく	いうまでもなく — needless to say
いいですよ	いいですよ — sure, that's fine
どうぞ	どうぞ — please, go ahead
どういたしまして	どういたしまして — you're welcome
とんでもない	とんでもない — not at all, no way
価値	かち — value, worth
安全	あんぜん — safety
最優先	さいゆうせん — top priority

I'm Yuuki, a Japanese teacher based in Tokyo. I've taught on italki as a Top 1% teacher and watched over 1,500 anime, so the phrases on this blog are ones I hear learners trip over in real lessons and in the shows themselves. For practice with feedback, Book a trial lesson · $13, or work through Japanese practice exercises first.

Sources: the author's own lessons and standard reference grammars.

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