PURPOSE: To intensify the electrostatic strength and obtain a semiconductor device of high quality by connecting a plurality of Schottky barrier diodes in series between the gate and source of a feild effect transistor in the forward direction with respect to the bias.

CONSTITUTION: Between the gate and source of an SB-FET 1, Schottky barrier diods 13 are connected in series in the forward direction. Thereby, the electrostatic strength can be intensified, and moreover, the forward voltage drop of the stack structure increases as the whole. Accordingly, the gate bias can be effectively applied without any leakage.