PURPOSE: To obtain different current amplification factors with the same element shape by setting the concentration of an impurity layer suitably by a method wherein the impurity layer of lower concentration than that of an epitaxial layer and the same polarity is formed between the emitter layer and the collector layer.

CONSTITUTION: The epitaxial layer 12 is provided with the P+ type emitter layer 14, P+ type collector layer 15, N+ type base contact layer 16, and N-- type impurity layer 17 formed between the emitter layer 14 and the collector layer 15. This impurity layer 17 has a lower concentration than that of the epitaxial layer 12 and the same polarity. Then, different current amplification factors can be obtained with the same element shape by suitably setting the concentration of the impurity layer 17.