〜と思う: How to Say 'I Think That…' in Japanese
What it means
と思う (と おもう) literally means "think that ~." You state an idea as a plain-form sentence, then tag と思う on the end to mark it as your opinion or guess. The と here is the quotative particle — the same と that quotes speech — so it works like an invisible "that": it wraps up the thought and hands it to 思う ("think"). The crucial rule: whatever comes before と stays plain form, even when the overall sentence is polite (〜と思います).
明日は雨が降ると思う。
あしたは あめが ふると おもう。
I think it'll rain tomorrow.
ヤッタンは行かないと思います。
ヤッタンは いかないと おもいます。
I think Yattan won't go.
The clause 行かない stays plain even though 思います is polite.
モチは学生だと思う。
モチは がくせいだと おもう。
I think Mochi is a student.
Noun + だ before と.
How to form it
Put the clause into plain form, then attach と思う. The only thing to watch is how each word type connects to と:
| Word before と | Add before と | Example |
|---|---|---|
| Verb (plain) | nothing | 行く → 行くと思う (I think (he'll) go) |
| い-adjective | nothing | 高い → 高いと思う (I think it's expensive) |
| な-adjective | だ | 元気 → 元気だと思う (I think (she's) well) |
| Noun | だ | 学生 → 学生だと思う (I think (he's) a student) |
Negatives and past tense work the same way — just make the plain clause negative or past first: 行かないと思う ("I think he won't go"), 高かったと思う ("I think it was expensive").
Saying what you think about things
このケーキはおいしいと思う。
この ケーキは おいしいと おもう。
I think this cake is delicious.
先生は来ないと思います。
せんせいは こないと おもいます。
I don't think the teacher will come.
Japanese negates the inner clause (来ない), not 思う.
あのレストランは静かだと思う。
あの レストランは しずかだと おもう。
I think that restaurant is quiet.
な-adjective 静か + だ.
Volitional + と思う — "I'm thinking of doing"
Put a volitional verb (the 〜よう / 〜おう form) before と思う and the meaning shifts from an opinion to an intention: "I'm thinking of doing / I plan to / I intend to."
日本に行こうと思う。
にほんに いこうと おもう。
I'm thinking of going to Japan.
行こう is the volitional of 行く.
ヤッタンは今日早く寝ようと思っています。
ヤッタンは きょう はやく ねようと おもっています。
Yattan is thinking of going to bed early today.
〜ようと思っている for a plan he's been holding.
This is close in feel to 〜つもり ("intend to"), but 〜ようと思う sounds a little softer and more like a decision you've just been turning over.
Third person: 〜と思っている
と思う states your own thought right now. To report what someone else thinks — an ongoing belief — Japanese uses the 〜ている form: 〜と思っている.
弟は試験に合格すると思っている。
おとうとは しけんに ごうかくすると おもっている。
My little brother thinks he'll pass the exam.
Third person's belief → 思っている.
You can also use 〜と思っている about yourself for a thought you've held for a while, not just a flash of opinion.
Common mistakes
- Using polite form before と思う. The inner clause must be plain: 行くと思います (✓), not
行きますと思います. Only 思う itself becomes polite. - Forgetting だ after nouns and な-adjectives. It's 学生だと思う and 静かだと思う — drop the だ and it's wrong.
- Negating 思う instead of the clause. "I don't think he'll come" is 来ないと思う (negate the verb), not 来ると思わない in everyday speech.
- Saying 友達と思う when you mean "think with a friend." The と思う here is the quotative と; the "together with" と is different. Context and word order keep them apart, but watch the particle's job.
Quick recap
- [plain form] + と思う = "I think that ~."
- The clause before と stays plain, even with 思います.
- Nouns and な-adjectives take だ: 学生だと思う.
- Volitional + と思う = "I'm thinking of / intend to" (行こうと思う).
- Someone else's thought → 〜と思っている.
Your turn
Choose the correct form before と思う (plain form, だ, or volitional).
Start the 5-question drill →Frequently asked questions
What form goes before と思う?
Plain form. Verbs and い-adjectives connect directly (行くと思う, 高いと思う); nouns and な-adjectives add だ (学生だと思う). The clause stays plain even when 思う becomes polite (〜と思います).
What does the と in と思う do?
It's the quotative particle — the same と used to quote speech. It packages your thought like an invisible 'that,' then hands it to 思う ('think').
What does 行こうと思う mean?
It uses the volitional (行こう) and means 'I'm thinking of going / I intend to go.' Volitional + と思う expresses an intention rather than an opinion.
How do I say what someone else thinks?
Use 〜と思っている: 弟は合格すると思っている ('my brother thinks he'll pass'). 〜と思う on its own describes your own thought in the moment.