1. Basic structure
| Component | Formation with ～と思う | Structure example | Notes |
|---|
| Clause | 普通形 + と + 思う | 明日は雨だと思う | Expresses thoughts/opinions |
| i/na-adj | い形容詞 + と + 思う／な形容詞 + だ + と + 思う | 難しいと思う／便利だと思う | Na-adj needs だ in writing |
| Noun | N + だ + と + 思う | 彼は医者だと思う | だ can be omitted in speech |
| Recollection | ～だった／～ではなかった + と + 思う | 学生だったと思う | “I remember/it seems it was …” |
| Negative | ～ない + と + 思う／～と + 思わない | 行かないと思う／行くとは思わない | Nuance difference (scope of negation) |
| State | ～と思っています | 結婚しようと思っています | An intention/thought that has formed and continues |
2. Main meanings & detailed analysis
- Expresses opinions, subjective conjecture: “I think/ I believe.”
- With volitional verbs: ～ようと思う expresses a momentary intention; ～ようと思っています expresses an intention that has been set.
- Negation: ～ないと思う (think it won't/doesn't …) vs ～とは思わない (do not go so far as to think …) differ in strength/emphasis.
- In conversation, んです/けど is often added to soften the statement: ～と思うんですが…
3. Example sentences
- この案が一番現実的だと思います。
I think this plan is the most realistic. - 明日は雨だと思う。傘を持っていこう。
I think it will rain tomorrow. Let's bring an umbrella. - 彼は真面目だと思わない。
I don't think he's serious. - 彼が来るとは思わなかった。
I didn't think he would come. - 来年留学しようと思っています。
I'm planning to study abroad next year. - 多分、間に合わないと思う。
I probably won't make it in time. - これは誤解だと思うんですが、もう一度確認してもいいですか。
I think this is a misunderstanding; may I check once more? - 昔はもっと静かだったと思う。
I remember it used to be quieter.
4. Usage & nuances
- “～と思います” is polite, less imposing; used in meetings and discussions.
- “～と思う” is neutral/colloquial. Combine with “たぶん/おそらく/きっと” to adjust certainty.
- Intention: Vようと思う/と思っています. For an intention right now: 今から勉強しようと思う。
5. Comparison, distinctions, and similar patterns
| Pattern | Meaning | Difference | Short example |
|---|
| ～と思う | I think/I believe | Personal, instantaneous opinion | 正しいと思う |
| ～と思っています | Thinking/planning | Ongoing state of thought | 引っ越そうと思っています |
| ～と考える | Consider/think (formal) | Logical, written style, more objective | 有効だと考える |
| ～気がする | It feels like… | Low certainty, intuition | 高い気がする |
| ～ように思う | It seems to me that… | Softens the statement | 無理のように思う |
6. Additional notes
- The first person “私は” is often omitted: 私は行くと思う → 行くと思う.
- “～だと思う” for na-adj/N: in conversation だ can drop, but in written exams you should keep だ.
- Here, と is the quotation particle, not a conditional.
- Scope of negation: AはBだと思わない (don't think A is B) differs from AはBではないと思う (think A is not B) in focus.
7. Variations & fixed expressions
- ～と思うんです（が）… (softens, opens a suggestion/counterpoint)
- ～かと思うと／～かと思えば (different context: no sooner … than …)
- どうかなと思う (a bit doubtful)
- ～ように（なる）と思う (light intention/wish)
8. Common mistakes & JLPT pitfalls
- Dropping だ in the wrong place: 彼は医者だと思う (written). In speech you can say: 医者だと思う／医者と思う.
- Mistaking と for a conditional: here と is always the quotation particle for 思う.
- Intention: ～と思う vs ～と思っています → choose correctly depending on whether it's “right now” or “already decided”.
- Negation: choose ～ないと思う or ～とは思わない to express the appropriate degree of negation for the JLPT question.
