A semiconductor device includes a sub-collector layer, a collector layer, a base layer, an emitter layer, and an emitter cap layer, which are sequentially laminated on a substrate. It also includes an emitter electrode, a base electrode, and a collector electrode, which are respectively formed on the emitter cap layer, the base layer, and the sub-collector layer. The sub-collector layer is made up of a first sub-collector layer adjacent to the substrate and a second sub-collector layer adjacent to the collector layer. In the area between adjacent device elements, the first sub-collector layer has an element insulating region created by ion implantation, and the second sub-collector layer has a recess-shaped element insulating region.