PURPOSE: To solve the problem that trade-off relation exists between preventing the latch up by elevating the concentration of the impurities in the region, where a channel is made by an insulated gate type bipolar transistor, and lowering channel resistance by lowering the concentration of impurities.

CONSTITUTION: The base current to a bipolar transistor is supplied not by the channel being generated by MOS structure, but by the carriers which are implanted from the high impurity concentration layer of the same conductivity type as the base layer contacting with an emitter electrode 9 by forming a potential gradient inside the base layer by the forward bias application to p-n junction or the electrostatic induction effect to the base layer and being exposed to the base layer 2 to the base layer.