Abstract: A semiconductor device serving as a semiconductor light-emitting element, a semiconductor light-receiving element, or a transistor, includes a first semiconductor layer of a first conductivity type having an ohmic electrode on one surface thereof, a second semiconductor layer of a second conductivity type formed on the other surface of the first semiconductor layer, source and drain regions formed in a surface region of the second semiconductor layer, source and drain electrodes respectively formed on the source and drain regions, an insulating layer formed on the second semiconductor layer between the source and drain regions, and a gate electrode formed on the insulating layer.