A semiconductor switch SW that includes a collector electrode C, an emitter electrode E and a gate electrode G, a Zener diode 5A configured to include one end electrically connected to the collector electrode C, the other end electrically connected to the gate electrode G, and n-type semiconductor layers and p-type semiconductor layers alternately arranged adjacent to each other, a Zener diode 5B configured to include one end electrically connected to the gate electrode G, the other end electrically connected to the emitter electrode E, and n-type semiconductor layers and p-type semiconductor layers alternately arranged adjacent to each other, are provided. The Zener diode 5A and the Zener diode 5B are configured so as not to allow the voltage of the gate electrode G to be increased to an on-threshold voltage of the semiconductor switch SW in the reverse bias application state.