A semiconductor device includes a semiconductor substrate and a MOS transistor. The semiconductor substrate has the first main surface and the second main surface facing each other. The MOS transistor includes a gate electrode (5a) formed on the first main surface side, an emitter electrode (11) formed on the first main surface side, and a collector electrode (12) formed in contact with the second main surface. An element generates an electric field in a channel by a voltage applied to the gate electrode (5a), and controls the current between the emitter electrode (11) and the collector electrode (12) by the electric field in the channel. The spike density in the interface between the semiconductor substrate and the collector electrode (12) is not less than 0 and not more than 3×108 unit/cm2. Consequently, a semiconductor device suitable for parallel operation is provided.