An electrostatic protection circuit includes a first transistor connected to an external terminal, a second transistor that is connected in series to the first transistor and that is in a normally OFF state. The electrostatic protection circuit includes a third transistor that is connected between a power source line and a gate of the first transistor, and a fourth transistor that is connected between the power source line and the gate of the first transistor in the opposite direction to the third transistor.