N3 Appearance, Tendencies, and Hearsay

~に違ちがいない: meaning, usage and examples

~に違ちがいない means: it must be... / I'm sure that...

Updated 9 November 2026 · By the My Senpai team · Spotted a mistake? Tell us

Examples

1. 彼女かのじょは日本人にほんじんに違ちがいない。

   She must be Japanese.

2. あんなに喜よろこんでいるから、試験しけんに合格ごうかくしたに違ちがいない。

   He looks so happy that he must have passed the exam.

3. 電気でんきがついているから、鈴木すずきさんは家いえにいるに違ちがいない。

   The lights are on, so Ms. Suzuki must be home.

4. こんなに人ひとが並ならんでいるから、おいしい店みせに違ちがいありません。

   With this many people in line, it must be a good restaurant.

When to use it

に違ちがいない means "must be" or "I am sure that". The speaker is strongly convinced of something, usually from evidence or a feeling: 電気でんきがついているから、家いえにいるに違ちがいない (the lights are on, so he must be home). It is common when you draw a conclusion from what you see.

Nuance

Slightly written or formal; in casual speech people often say きっと～と思おもう or 絶対ぜったい～だ. The conviction comes from the speaker's own judgment, which can be intuitive. It is not used for facts the speaker already knows for certain.

Compare

はずだ is a logical expectation based on facts or plans: 3時じに出でたから、もう着ついたはずだ (he left at 3, so he should be there). に違ちがいない is a strong personal conviction. かもしれない is only a possibility. はずがない means "there is no way", the opposite of に違ちがいない.

Tip: No だ before に違ちがいない: 本当ほんとうに違ちがいない, not 本当ほんとうだに違ちがいない. Use はずだ when you are reasoning from a schedule or a fact.