A field-effect transistor provided with a substrate, a channel layer, a carrier supply layer, a source electrode, a drain electrode, a gate electrode, a first insulating layer that is laminated on the carrier supply layer between the source electrode and the drain electrode, and suppresses current collapse, an opening that is formed between an edge of the first insulating layer opposing the drain electrode and the drain electrode, and a second insulating layer that is laminated on the carrier supply layer exposed in the opening.