Plain Form vs Masu Form in Japanese: When to Use Which Register

2026年4月23日

Japanese has two main verb registers: the plain form (dictionary form) and the polite masu form. Choosing the right one depends on the situation and your relationship with the listener.

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At a Glance

Form	Also Called	When to Use	Example
Plain form (普通体)	Dictionary form, casual form	With close friends, family, in writing, before particles	食べる
Masu form (丁寧体)	Polite form	With strangers, at work, with superiors	食べます

The Masu Form (丁寧体) — Polite Speech

Use masu form when speaking to people you don’t know well, at work, with customers, teachers, or anyone older/senior.

毎朝6時に起きます。 — I get up at 6 every morning. (polite)

どこに行きますか？ — Where are you going? (polite)

The Plain Form (普通体) — Casual Speech

Use plain form with close friends, family members, and in informal situations.

毎朝6時に起きる。 — I get up at 6 every morning. (casual)

どこ行くの？ — Where are you going? (very casual, with のか softened to の)

Plain Form is Required Before Certain Words

Even in polite speech, plain form is required before certain grammar patterns:

Pattern	Example	Meaning
〜と思う	行くと思う	I think (they) will go
〜と言う	食べると言った	Said that (they) eat
〜から (because)	雨だから行かない	Because it’s raining, I won’t go
〜ので (because)	疲れたので寝る	Because I’m tired, I’ll sleep
〜が (but)	行くが、難しい	I’ll go, but it’s difficult

Yuka

So I can use polite masu form everywhere and be safe?

Rei

In daily conversation with new people, yes. But if you speak to close friends in masu form all the time, they might find it cold or distant! Japanese uses different registers to signal closeness.

Yuka

And what about when I’m writing a diary or essay?

Rei

Plain form for personal writing like diaries. Masu form or desu-masu for formal essays and letters. Newspapers and books generally use plain form.

Mixing Forms — What’s Natural?

Within one sentence, you can mix forms at certain points. End the sentence in the register you want, but use plain form in embedded clauses.

彼が来ると思います。 — I think he will come. (思います = masu; 来る = plain, inside the clause)

Common Mistakes

Situation	Mistake	Correct
Ending sentences in plain form at work	明日行く。	明日行きます。
Using masu before と思う	行きますと思う	行くと思う
Plain form with strangers in casual situations	Context matters — short polite is safest	行きます