A structure is provided that ensures a low on-resistance and a better blocking effect. In a lateral type SIT (Static Induction Transistor) in which a first region is used as a p+ gate and a gate electrode is formed on the bottom of the first region, the structure is built such that the p+ gate and an n+ source are contiguous. An insulating film is formed on the surface of an n− channel, and an auxiliary gate electrode is formed on the insulating film. In addition, the auxiliary gate electrode and the source electrode are shorted.