JLPT N2

いったん～ば

Once (A happens), then (B)

Structure

いったん + Verb-ba form + Sentence

This pattern emphasizes that as soon as a certain condition or action occurs, a specific and often irreversible consequence or state will follow.

いったん決まれば、もう変えられない。

Once it's decided, it can't be changed anymore.

Confusing it with a simple conditional; いったん adds a sense of finality or strong consequence.

Think of いったん meaning 'temporarily' or 'once', combined with the conditional ~ば, to mean 'once this condition is met, then...'

Import an article and tap any sentence using it. The explanation comes back about the sentence in front of you, not a textbook example.