# に違いない: must be; no doubt

> Learn how to use に違いない, a JLPT N3 Japanese grammar point meaning must be; no doubt, with structure, nuance, examples, mistakes, and comparisons.

JLPT level: N3 · Updated: 2026-05-17 · Canonical: https://hane-app.com/blog/n3-ni-chigai-nai/

**に違いない** means **must be; no doubt**. It is a **JLPT N3** grammar pattern used to **state a strong conclusion based on evidence**.

This grammar point often appears in **neutral** Japanese. If you want to **state a strong conclusion based on evidence**, **に違いない** is a useful pattern to learn.

## What does に違いない mean?

Use **に違いない** when you want to **state a strong conclusion based on evidence**.

Natural translations include:
- must be; no doubt
- must be
- must be / no doubt

## How to form に違いない

Plain form + に違いない / Noun + に違いない

Examples of the pattern:
- 本当 に違いない
- 知っているに違いない
- 大変だったに違いない

## When is に違いない used?

Use **に違いない** in situations like:
- explaining context clearly
- answering JLPT reading questions
- making natural Japanese sentences

Tone and register:
- neutral
- Common in JLPT reading, grammar questions, and natural Japanese sentences

## に違いない example sentences

- 彼はもう家に着いたに違いない。 — He must have arrived home already.
- この足跡は犬に違いない。 — These footprints must be from a dog.
- 彼女は試験のために一生懸命勉強したに違いない。 — She must have studied hard for the exam.
- あの店は人気があるに違いない。 — That shop must be popular.
- こんなに静かなら、みんな帰ったに違いない。 — If it is this quiet, everyone must have gone home.

## Nuance of に違いない

The key nuance is **a practical way to express “must be; no doubt” with the right level of emphasis**.

This matters because **に違いない** does more than translate one English phrase. It tells the reader how the speaker is framing the situation, whether as emphasis, contrast, obligation, approximation, or evidence.

For example:
- In context, it sounds natural when the surrounding sentence supports the nuance.
- Compared with **[はずだ](/blog/n4-hazu-da/)**, it has a different focus and level of formality.

## に違いない vs はずだ

Both **に違いない** and **[はずだ](/blog/n4-hazu-da/)** can appear in related situations, but they are different.

**に違いない**:
- means **must be; no doubt**
- fits the specific N3 pattern and nuance explained above

**[はずだ](/blog/n4-hazu-da/)**:
- はずだ is expectation based on logic; に違いない is stronger certainty

Quick contrast examples:
- Target: 彼はもう家に着いたに違いない。 — He must have arrived home already.
- Compare: Try replacing it with **[はずだ](/blog/n4-hazu-da/)** and check whether the nuance still matches.

## Common mistakes with に違いない

Watch out for these mistakes:
- Using に違いない with the wrong form
- Confusing に違いない with はずだ
- Translating it too literally instead of reading the whole sentence

## Is に違いない on the JLPT?

Yes. **に違いない** is commonly taught as **JLPT N3** 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 に違いない

Try making your own sentences with these prompts:
- Write one sentence using に違いない.
- Contrast に違いない with はずだ.
- Make a JLPT-style sentence with a clear context.

## Learning path for に違いない

To learn **に違いない** efficiently, review basic particles like について and に, then focus on the relationship each formal marker creates.

1. First, make sure you can form **に違いない** without looking at the pattern chart.
2. Next, compare it with [はずだ](/blog/n4-hazu-da/), [に対して（にたいして）](/blog/n3-ni-taishite/). These patterns are close enough that choosing between them helps you understand the nuance.
3. Finally, write reading-style sentences about society, research, policy, opinions, and reports; then check whether replacing **に違いない** with [にとって](/blog/n3-ni-totte/) changes the meaning.

## Related grammar to review next

- [はずだ](/blog/n4-hazu-da/) — because it is the closest comparison used in this article.
- [に対して（にたいして）](/blog/n3-ni-taishite/) — because it is another formal relation marker common in JLPT reading.
- [にとって](/blog/n3-ni-totte/) — because it is another formal relation marker common in JLPT reading.
- [について](/blog/n3-ni-tsuite/) — because it is another formal relation marker common in JLPT reading.

## Learn に違いない with Hane

If you want to review **に違いない** 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](/blog/)
- [JLPT N3 grammar lessons](/blog/n3/)