In an embodiment, provided is a semiconductor device in which a normally-on type FET; a capacitor having one electrode electrically connected to a gate of the FET and the other electrode electrically connected to an input terminal; and a diode having an anode electrode electrically connected to the gate of the FET and a cathode electrode electrically connected to a source of the FET are formed on the same chip on which the FET is formed. Also, the capacitor may have a structure in which an insulation film such as a dielectric substance is formed on a gate drawn electrode of the FET, and a metallic layer is formed on the insulation layer.