～はずがない

～はずがない expresses strong conviction that something is impossible. はず is a noun meaning “expectation”, so the pattern literally says “the expectation (that this is true) does not exist” — English “there's no way” or “it can't be”.

It follows the plain form of verbs and い-adjectives, な-adjectives with な, and nouns with の. The speaker is not just guessing: some reason or knowledge backs up the denial.

1. Denying that someone would do something

Use ～はずがない after a verb to reject an action as unthinkable, often based on what you know about the person.

2. Denying a description

The same pattern rejects a claimed quality or identity. With い-adjectives it attaches directly; with nouns, add の.

～はずがない is the negative counterpart of はずだ (“should be, is supposed to be”), and the opposite of ～かもしれない: where ～かもしれない admits a possibility, ～はずがない rules it out completely.

How to form it

Plain form + はずがない (な-adjective + なはずがない, Noun + のはずがない)

• つく = to tell (a lie) → つくはずがない = would never tell
• 安い（やすい）= cheap → 安いはずがない（やすいはずがない）= can't be cheap
• 本当（ほんとう）= true → 本当のはずがない（ほんとうのはずがない）= can't be true

Key idea

はずがない means that the expected possibility does not exist. Based on what you know, you reject the possibility outright. Reach for it when “probably not” is too weak and you mean “absolutely not”.