SEMICONDUCTOR DEVICE

A collector layer, a base layer, an emitter layer, and an emitter mesa layer are placed above a substrate in this order. A base electrode and an emitter electrode are further placed above the substrate. The emitter mesa layer has a long shape in a first direction in plan view. The base electrode includes a base electrode pad portion spaced from the emitter mesa layer in the first direction. An emitter wiring line and a base wiring line are placed on the emitter electrode and the base electrode, respectively. The emitter wiring line is connected to the emitter electrode via an emitter contact hole. In the first direction, the spacing between the edges of the emitter mesa layer and the emitter contact hole on the side of the base wiring line is smaller than that between the emitter mesa layer and the base wiring line.