に相違ないni soui nai“without a doubt; certainly”

に相違ない means without a doubt; certainly. It is a JLPT N2 Japanese grammar pattern used to make a formal assertion that something is surely true.

This grammar point often appears in advanced reading, formal writing, notices, essays, and careful conversation. If you want to read Japanese with more nuance, に相違ない is a useful pattern to learn because it shows the speaker’s logic, stance, or emphasis.

What does に相違ない mean?

Use に相違ない when you want to make a formal assertion that something is surely true.

Natural translations include:

• without a doubt; certainly
• depending on context
• in a way that matches the speaker’s emphasis

How to form に相違ない

Plain form + に相違ない

Examples of the pattern:

• これは本物に相違ない。
• 彼の努力が成功の理由に相違ない。
• この資料は重要な証拠に相違ない。

When is に相違ない used?

Use に相違ない in situations like:

• reading formal explanations, announcements, or essays
• making a point more precise than a basic grammar pattern would
• connecting two ideas with a clear nuance

Tone and register:

• usually neutral to formal
• common in JLPT N2 reading passages, news, notices, and business-like writing

に相違ない example sentences

• これは本物に相違ない。 — This is undoubtedly genuine.
• 彼の努力が成功の理由に相違ない。 — His effort is certainly the reason for success.
• この資料は重要な証拠に相違ない。 — This document is undoubtedly important evidence.
• その判断は正しいに相違ない。 — That judgment is surely correct.
• 多くの人が彼女を支持するに相違ない。 — Many people will undoubtedly support her.

After reading each sentence, ask what job に相違ない is doing. Is it limiting, adding, conceding, asserting, or describing a condition?

Nuance of に相違ない

The key nuance is make a formal assertion that something is surely true.

For example:

• In formal writing, に相違ない often sounds more precise than a casual equivalent.
• Compared with に違いない, it has a different tone or scope even when the English translation looks similar.

に相違ない vs に違いない

に相違ない:

• fits the N2 nuance explained above
• often sounds more specific, formal, or emphatic

に違いない:

• is usually broader, simpler, or used in a different register
• may be better in casual conversation depending on the sentence

Quick contrast examples:

• これは本物に相違ない。
• Try rewriting the sentence with に違いない and notice whether the tone or meaning changes.

Common mistakes with に相違ない

Watch out for these mistakes:

• Translating it too literally and missing the function in context
• Confusing it with に違いない just because the English translation overlaps
• Using it in casual speech when a simpler pattern would sound more natural

A helpful practice method is to write one sentence with に相違ない, then compare it with a related grammar point. Explain the difference in your own words.

Is に相違ない on the JLPT?

Yes. に相違ない is commonly taught as JLPT N2 grammar.

That means learners should be able to:

• recognize it in reading
• understand its nuance in context
• use it in simple original sentences

Practice questions for に相違ない

• Write one sentence that clearly needs に相違ない.
• Write a second sentence with に違いない and compare the nuance.
• Find a notice, article, or dialogue where this kind of meaning would be natural.

Learning path for に相違ない

To learn に相違ない efficiently, follow a path that matches this pattern’s real function.

1. First review the formation so the base structure feels natural.
2. Then compare に相違ない with に違いない and the related lessons below.
3. Finally, write your own sentence where the context makes に相違ない necessary.

Related grammar to review next

• n3 ni chigai nai — must be; no doubt.
• に決まっている — it must be; surely.
• にほかならない — nothing other than.

Learn に相違ない with Hane

If you want to review に相違ない together with the related patterns above, Hane helps you connect grammar, kanji, and vocabulary in short, focused sessions.

Browse more lessons here:

• All grammar lessons
• JLPT N2 grammar lessons