PURPOSE: To position each electrode section with high accuracy by simultaneously forming each electrode contact window for a source, a drain and a gate by using one mask on the formation of the contact windows.

CONSTITUTION: An N type GaAs semiconductor layer 12 is grown on a GaAs substrate 11, and an SiO2 film 13, a mask film 14 and a negative type photo- resist film 15 are formed on the layer 12. the film 15 is patterned, and an opening is bored to the film 14 while using the film 15 as a mask. Contact windows 13S, 13D, 13G for each electrode of a source, a drain and a gate are formed to the film 13 while employing the film 15 and the film 14 as masks. A positive type photo-resist film 16 is shaped. The window 13G is formed to the film 16. A WSi film 17 as a metallic film for forming a Schottky junction is shaped. The films 15 and 16 are removed. Accordingly, patterning by a lift-off method is executed, and a gate electrode 17G is formed while each electrode contact window 13S and 13D for the source and the drain appear.