PURPOSE: To obtain a base resistance value for a desired bypass by disposing a bypass means consisting of only PNP and NPN transistors in an array between a base and an emitter in a switching transistor.

CONSTITUTION: P type semiconductor regions 2, 3, 5 are connected to an N type semiconductor region 1, N type semiconductor regions 4a, 4b, 4c are connected to the P type semiconductor region 3, and an N type semiconductor region 6 is formed to the P type semiconductor region 5. A PNPTr using the region 1 as a base, the region 2 as an emitter and the region 3 as a collector is shaped as an injector Q1, an NPNTr employing the region 1 as an emitter, the region 3 as a base and the regions 4a, 4b, 4c as collectors as a switching TrQ2 and a PNPTrQ3 and an NPNTrQ4 using the regions 1, 3, 5 as bases, emitters and collectors and the regions 1, 5, 6 as emitters, bases and collectors as bypass means.