1.
must be; there is no doubt that; certainly
Expresses strong conviction or certainty about something. Attaches to verbs (plain form), adjectives, and nouns (+に). More formal than ～に決まっている and softer than ～はずだ.
彼は知っているに違いない。
He must know about it.
あの音は雷に違いない。
That sound must be thunder.
こんなに混んでいるということは、人気のある店に違いない。
The fact that it's this crowded means it must be a popular restaurant.
GRAMMAR:
Attaches to the plain form of verbs and i-adjectives, na-adjectives (+に/だったに), and nouns (+に/だったに).
- Verb: 降っているに違いない (it must be raining)
- i-adj: 高いに違いない (it must be expensive)
- Noun: 学生に違いない (must be a student)
USAGE:
Expresses the speaker's strong belief based on evidence or reasoning. Unlike ～はずだ, which is based on logical expectation, に違いない conveys personal conviction. Often used when drawing conclusions from observable facts.
SIMILAR EXPRESSIONS:
- ～に決まっている: more casual and assertive; "obviously"
- ～はずだ: based on logical expectation rather than conviction
- ～だろう: weaker certainty; "probably"