A semiconductor device includes a substrate common to a first field effect transistor and a second field effect transistor, a channel layer of a first conductivity type formed on the substrate and common to the first and second field effect transistors, a an upper compound semiconductor layer formed on the channel layer and common to the first and second field effect transistors, a compound semiconductor region of a second conductivity type formed in the same layer as the upper compound semiconductor layer, a gate electrode of the first field effect transistor in ohmic contact with the compound semiconductor region, and a gate electrode of the second field effect transistor in Schottky contact with the upper compound semiconductor layer.