A semiconductor device comprises an insulated-gate field effect transistor section including an n-type emitter area (3) and an n<-> silicon substrate (1) opposed across a p-type body area (2), and a gate electrode (5a) opposed across a gate insulator (4a) in the p-type body area (2). The semiconductor device further comprises a stabilizer plate (5b) consisting a conductor or a semiconductor, which is opposed to the n<-> silicon substrate (1) across a plate insulator (4, 4b) to form a capacitor between the stabilizer plate and the n<-> silicon substrate (1). The stabilizer plate capacitance between the stabilizer plate (5b) and the n<-> silicon substrate (1) is greater than the gate-drain capacitance between the gate electrode (5a) and the n<-> silicon substrate (1).
