What it means
に相違ない expresses a strong conclusion that something is certain or beyond doubt. It is used when the speaker or writer judges that the available evidence makes the statement highly reliable. The expression is especially common in formal writing, reports, announcements, and serious speech.
Usage note
に相違ない is considerably more formal than に違いない and can sound stiff in casual conversation. Its conventional polite counterpart is に相違ありません. With a noun, it attaches directly; with a na-adjective, the formal copula である is normally inserted.
How to use it
この報告書は事実に相違ありません。
This report is undoubtedly factual.
彼の説明は明快であるに相違ありません。
His explanation is undoubtedly clear.
この判断が正しいに相違ありません。
This judgment is undoubtedly correct.
この計画は成功するに相違ありません。
This plan will undoubtedly succeed.
この報告書は事実に相違ない。
This report is undoubtedly factual.
彼の説明は明快であるに相違ない。
His explanation is undoubtedly clear.
この判断が正しいに相違ない。
This judgment is undoubtedly correct.
この計画は成功するに相違ない。
This plan will undoubtedly succeed.