JLPT N4 grammar
〜にちがいない — Meaning & Examples
Must be, no doubt (95%). Slightly formal. Casual speakers often prefer 絶対〜と思う instead.
〜にちがいない and Choosing Between Them
〜にちがいない — "must be / no doubt"
Formation: plain form + にちがいない (な-adj and nouns drop だ)
あの人は先生にちがいない。
= That person must be a teacher.
彼は疲れているにちがいない。
= He must be tired.
This is strong and slightly formal — common in writing, mysteries and news. In casual speech people often say 絶対〜と思う instead:
絶対そうだと思う。 = I am sure that is it.
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Quick decision guide:
You have no real evidence, just a possibility → かもしれない
You are making a general prediction → でしょう
You have a specific reason to expect it → はずだ
You are convinced by the evidence → にちがいない
Try it — your friend has not arrived:
道に迷ったかもしれない。 — Maybe he got lost. (no idea)
もうすぐ来るでしょう。 — He will probably be here soon. (general)
7時に出たから、もう着くはずだ。 — He left at 7, so he should be here. (reasoning)
電車が止まったにちがいない。 — The trains must have stopped. (you just saw the news) 🚉
Practice questions
Try these 2 questions on 〜にちがいない. Pick an answer in your head, then open “Show answer”.
1. Which expresses the LOWEST confidence?
- 〜にちがいない
- 〜はずだ
- 〜かもしれない
- 〜でしょう
Show answer
Answer: 〜かもしれない
The dial runs かもしれない (maybe, 30–50%) → でしょう (probably) → はずだ (should be) → にちがいない (must be, ~95%).
2. You just saw on the news that the trains have stopped. Your friend is late. The most natural comment is?
- 道に迷ったかもしれない
- もうすぐ来るでしょう
- 来るはずがない
- 電車が止まったにちがいない
Show answer
Answer: 電車が止まったにちがいない
You have strong evidence, so にちがいない (must be, no doubt) fits. かもしれない would understate what you know.
Practise 〜にちがいない in the free app
This point is part of the “🤔 How Sure Are You? — でしょう・かもしれない・はず・にちがいない” lesson in A Star Japanese. Study it with examples, a quiz, flashcards and timed JLPT N4 mock exams. Free on iPhone and Android.
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Related N4 grammar points
From the same lesson: 🤔 How Sure Are You? — でしょう・かもしれない・はず・にちがいない
Frequently asked questions
What does 〜にちがいない mean?
Must be, no doubt (95%). Slightly formal. Casual speakers often prefer 絶対〜と思う instead.
Is 〜にちがいない on the JLPT N4 test?
〜にちがいない is taught in the JLPT N4 grammar course in A Star Japanese (lesson “🤔 How Sure Are You? — でしょう・かもしれない・はず・にちがいない”), so it is a pattern learners at this level are expected to recognise. The JLPT does not publish an official grammar list, so treat this as a study guide rather than an official requirement.
How can I practise 〜にちがいない?
Open the “🤔 How Sure Are You? — でしょう・かもしれない・はず・にちがいない” lesson in the free A Star Japanese app for iPhone and Android. It has examples, a quiz after every lesson, flashcards with spaced repetition and timed JLPT N4 mock exams, with no ads.