に違いない

にちがいない

There is no doubt that, I'm sure

彼かれらは、先生せんせいがいなくなったらふざけるに違ちがいない。

There is no doubt that they will muck around once the teacher has gone.

Explanation

「に違いない」 means 'must be' or 'surely'. The speaker has caught a clear clue and, after reasoning, is sure there is no other possibility. It is a subjective judgement with very high confidence. It often goes with 「きっと」 or 「確かに」: 「あの店はいつも並んでいる。きっとおいしいに違いない」 (There's always a queue at that shop. It must be good). It follows the plain form; nouns and na-adjectives use the bare stem, with no 「だ」.

Mixed up with

「に違いない」 is the speaker's own strong conviction. 「はずだ」 is 'it should be so' based on objective logic or common sense, with something checkable behind it.

Never add 「だ」 after a noun or na-adjective: 「×学生だに違いない」, 「×親切だに違いない」. Wrong choices often include 「だ」.

Easily confused withに決まっている・に違いない: the difference ›に相違ない・に違いない: the difference ›

Examples

あなたが美味おいしいというなら、美味おいしいに違ちがいない。
If you say that it is good, I have no doubt that it is.
今いまのピンポンは近所きんじょの子供こどものいたずらに違ちがいない。
There's no doubt that the doorbell I just heard must have been a prank by the neighbor's kid.
あの顔立かおだちからして、日本人にほんじんに違ちがいない。
Judging from that face, he must be Japanese.
タナカ君くんは全然ぜんぜん料理りょうりを食たべてない。この料理りょうりが嫌きらいに違ちがいない。
Tanaka-kun is not eating his food at all. There is no doubt that he does not like it.
彼女かのじょは病気びょうきに違ちがいない。
There is no doubt that she is sick.
こんなに遅おそいなんて…、何なにかあったに違ちがいない。
Being so late... there is no doubt that something happened.
あの言いい方かただと、何なにか隠かくしているに違ちがいない。
From the way he speaks, there is no doubt that he is hiding something.
大雪おおゆきが降ふって大変たいへんだったに違ちがいない。
I am sure that it was tough after that heavy snowfall.
あんな転ころび方かたをして、痛いたいに違ちがいない。
Falling in that way, there is no doubt that it hurts.
電話でんわの声こえからいって、２０代だいに違ちがいない。
Judging from the voice on the phone, I am sure they were in their twenties.
最近さいきん全然ぜんぜん休やすみがないから、彼かれは疲つかれているに違ちがいない。
He hasn't rested at all recently, so I am sure he is tired.
あの格好かっこうからいって、あの人ひとはお金かね持もちに違ちがいない。
Judging from appearances, I am sure that person is loaded.
あの体からだつきからいって、相当そうとう筋きんトレをしているに違ちがいない。
Judging from his body build, there is no doubt that he is working out a lot.
何回なんかい呼よび鈴りんを押おしても出でてこない。きっと寝ねているに違ちがいない。
No matter how many times I ring the bell, they won't come out. I am sure they are sleeping.
現場げんばで彼かれの髪かみの毛けが見みつかったので、彼かれは犯人はんにんに違ちがいない。
His hair was found at the scene. There is no doubt that he is the offender.
あの人ひとはカメラマンに囲かこまれているから、有名人ゆうめいじんに違ちがいない。
That person is surrounded by photographers. They must be famous.

に違いない

Explanation

Mixed up with

Examples

Tested 4 times in past papers