ものなら

ものなら after a potential verb means "if only I could": the speaker wishes for something they know is hard or impossible. The second half says what they would do, usually with たい.

A verb that already means "can happen", like かなう叶う, takes ものなら directly.

ものなら or たら

ものなら says the condition is out of reach. For something that could easily happen, use たら or ば.

• × 時間があるものなら、行きたい → 時間があったら、行きたい

Usage notes

These go beyond a wish for the impossible.

A dare

Followed by きごう〜てみろ or another order, ものなら becomes a challenge: "try it if you can". The speaker doubts that the listener can.

〜ようものなら: a warning

After a volitional form, ものなら means "if you so much as": the smallest step would bring something bad. The second half is the consequence.

Register

ものなら belongs to written Japanese and serious speech, apart from the dare, which is rough spoken language. In conversation できれば or たら carries the plain wish.