〜に相違ない

Without Doubt/certainly

Level 4Sounds Like nisouinai

〜に相違ない（にそういない） is a formal way to say 'without a doubt' or 'certainly.' It is used when the speaker is highly confident in their conclusion based on objective facts or logical reasoning.

How It Works

〜に相違ない is primarily a written expression（書き言葉） used in formal reports, legal documents, or academic writing. It expresses a definitive declaration.

1. Usage and Nuance:
While it translates similarly to 'must be,' it carries a tone of official certainty. It is not used for casual guesses or personal feelings, but rather for conclusions drawn from evidence（証拠）. In very formal or legal contexts, the polite form 〜に相違ありません is used to confirm facts (e.g., 'There is no mistake in the above'). The question form 〜に相違ないか？ is also used by authorities to confirm statements.

2. Formation:

  • Verbs: Plain form + に相違ない (e.g., 合格したに相違ない)
  • Nouns: Noun + に相違ない (e.g., 犯人に相違ない). For extra formality, である is often added: Noun + であるに相違ない.
  • い-Adjectives: Plain form + に相違ない (e.g., 難しいに相違ない)
  • な-Adjectives: Stem + に相違ない (e.g., 困難に相違ない). Like nouns, である can be added: 困難であるに相違ない.

3. Register:
In daily conversation, this pattern sounds overly dramatic or stiff. In spoken Japanese, に違いない or に決まっている are much more common.

Examples (4)

  1. 証拠から判断して、犯人はあの男に相違ない。

    Judging from the evidence, the criminal is undoubtedly that man.

    Word by Word: Evidence from judging, criminal as-for that man (no discrepancy).

    This is a classic use of the pattern in a formal or investigative context where a conclusion is drawn from facts.

  2. これだけの反対がある以上、計画の遂行は難しいに相違ない。

    Given this much opposition, carrying out the plan will certainly be difficult.

    Word by Word: This much opposition exists since, plan's execution as-for difficult (no discrepancy).

    Here, the speaker uses logical reasoning (the amount of opposition) to state a certain outcome using an い-adjective.

  3. 彼が黙っているのは、真実を知っているからに相違ない。

    The reason he is staying silent is undoubtedly because he knows the truth.

    Word by Word: He (subject) silent-is nominalizer as-for, truth (object) knowing because (no discrepancy).

    The pattern can follow 'から' (because) to emphasize that the reason for something is certain.

  4. この文書は、彼自身の手によって書かれたものに相違ありません。

    This document was undoubtedly written by his own hand.

    Word by Word: This document as-for, him self's hand by written thing (no discrepancy - polite).

    This example demonstrates the polite form 〜に相違ありません, often used in formal testimony or official reports.

Common Mistakes

  • Using the pattern in casual daily conversation.

    明日のパーティーは楽しいに相違ない！
    明日のパーティーは絶対に楽しいに違いない！

    〜に相違ない is too stiff for a casual party. Use に違いない or に決まっている for personal feelings or social situations.

  • Adding 'だ' before the pattern when using nouns.

    彼は犯人だに相違ない。
    彼は犯人に相違ない。 (or 犯人であるに相違ない)

    You should not use the casual copula 'だ' before に相違ない. Attach it directly to the noun or use the formal 'である'.

How It Connects

Tap a pattern to see what it builds on and what it leads to.

〜に相違ないLevel 4Without Doubt/certainly

Learn This First

〜に相違ない is a formal expression used to state a strong conviction or certainty, equivalent to 'without a doubt' or 'must be'. It is primarily used in written Japanese or formal speeches. To understand it, learners should already be familiar with its more common counterpart 〜に違いない and have a solid grasp of how to connect various parts of speech to auxiliary expressions.

Words in This Pattern

相違ない相違