PURPOSE: To reduce base concentration by previously giving concentration distribution denying the doping concentration distribution of a subsequently introduced P-type dopant into a mother semiconductor layer and doping an N-type dopant.

CONSTITUTION: When a base region is manufactured by inverting the conductivity type of the same mother semiconductor layer as an emitter and a collector region by using an ion implantation method or an impurity diffusion method, doping denying the effect of the distribution of an impurity caused by the result of these ion implantation and impurity diffusion into the mother semiconductor layer is conducted previously. Consequently, base impurity concentration can be diminished and base width reduced, this improving current gains. The scale- down of base width results in the shortening of carrier transit time in the base region, thus realizing a lateral type bipolar transistor having excellent high-frequency characteristics.