The electrostatic protection device provided between an input/output terminal and an internal circuit of a semiconductor device according to the present invention has a first insulated gate field effect transistor (MOS transistor) and a second MOS transistor that are connected mutually in parallel between an input/output wiring connected to the input/output terminal and an electrode wiring of a prescribed potential, where the first MOS transistor and the second MOS transistor are MOS transistors of the same channel type, the second MOS transistor has s higher drive capability than the first MOS transistor, and the electrostatic protection device is formed such that it is started by the first MOS transistor.