～に違いない — There's No Doubt
Expresses the speaker's strong conviction: 'it must be ~ / there's no doubt that ~'. It states a confident conclusion drawn from evidence or reasoning, stronger than はず or だろう. The speaker is almost certain, though not stating a proven fact.
Structure
[Plain form (na-adj/noun drop だ)] + に違いない
Examples
電気が消えているから、彼はもう寝たに違いない。
Denki ga kiete iru kara, kare wa mou neta ni chigainai.
The lights are off, so he must have already gone to sleep.
Confident conclusion from evidence (lights off) + に違いない
この味は本場の料理に違いない。
Kono aji wa honba no ryouri ni chigainai.
This taste must be authentic local cuisine.
Noun 料理 attaches directly (no だ) + に違いない
あんなに勉強したのだから、合格するに違いない。
Anna ni benkyou shita no da kara, goukaku suru ni chigainai.
Since he studied that much, he'll surely pass.
Verb 合格する + に違いない for a strong prediction
• Expresses the speaker's own strong conviction, not objective proof. • Noun/na-adjective attach directly (drop だ): 学生に違いない. • More emphatic and formal than だろう / でしょう.
Commonly confused with
The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones ～に違いない is tested against.
vs はずだ
はずだ is a logical expectation based on known facts/rules; に違いない is the speaker's subjective strong conviction and feels more emotionally certain.
vs だろう
だろう is a soft guess ('probably'); に違いない expresses near-certainty and is much stronger.
More hearsay & conjecture
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