To improve the output characteristic of a field-effect transistor as a high-output element, operating efficiency and strain characteristic of the transistor, and noise characteristic of the transistor as a low-noise element by providing an opening after the crystal of an ohmic contact layer is grown and forming a channel layer and a Schottky layer in the opening.

After a GaAs buffer layer 2 and an n--type GaAs ohmic contact layer 6 are epitaxially grown on a substrate 1, an opening is formed through the layer 6 by selectively removing the layer 6 by using a dielectric film 16 as a mask so that the buffer layer 2 can be exposed on the bottom of the opening. Then an n-type GaAs channel layer 11, an n-type AlGaAs Schottky contact layer 13, and an active layer composed of an n--type GaAs field relieving layer 13 are grown on the exposed buffer layer 2 in the opening. Therefore, the hetero-contact between the channel layer 11 and ohmic contact layer 6 can be eliminated.