To sufficiently increase the breakdown voltage and the current gain in a heterobipolar transistor device.

A collector layer 12 composed of n-type gallium nitride, a base layer 13 composed of p-type silicon germanium, and an emitter layer 14 composed of n-type gallium nitride are successively formed on a semiconductor substrate 11 composed of p-type silicon according to selective growth process. Thus, since a valence band energy difference ΔEv between the emitter layer 14 and the base layer 13, and a valence band energy difference ΔEv between the collector layer 12 and the base layer 13 are increased, both the breakdown voltage and the current gain are increased.