Abstract: A semiconductor device includes an emitter region, a collector region provided directly under the emitter region, and a two-region base structure. The first base region is interposed between the emitter and collector regions, and the second base region supports the collector region. The aforementioned regions have a progressively higher impurity concentrations, with the collector region having an impurity concentration higher than that of the first base region, the second base region having an impurity concentration higher than that of the collector region, and the emitter region having an impurity concentration higher than that of the base region. Also included is a resistance region formed, in one embodiment, from a projecting end portion of one of the base layers. The projecting end portion of the base is fabricated so that both base portions contact one another in the resistance region, and consequently both base portions are of the same potential.