Page 510 - Basic Japanese

chigai nai is based on the construction chigai wa nai ‘there is no

error.’ After a noun, an imperfect or perfect verb, or an
adjective, the expression ni chigai nai means ‘without a

doubt,’ ‘no doubt,’ ‘certainly,’ or ‘surely.’ It is often
translated as ‘must have done,’ ‘must be,’ etc., but of

course this is not the ‘must’ of obligation (= ‘has to’).

Pasuwādo wa kore ni chigai arimasen.

The password must be this one. I’m sure this is
it.

Okamoto-san ga kuru ni chigai arimasen.
Mr. Okamoto will surely come.

Watashi no pasokon wa uirusu ni kansen shita ni chigai
arimasen.
My PC must have been infected by viruses.

Watashi no shujin ni chigai arimasen.

That is surely my husband.

Shigoto ga iya datta ni chigai arimasen.
He certainly disliked his job.

Anna ii ie wa takai ni chigai arimasen.
Such a nice house must be expensive.