A semiconductor device comprises a first base layer of a first conductive type which has a first surface and a second surface; a second base layer of a second conductive type which is formed on the first surface; first and second gate electrodes which are formed by embedding an electrically conductive material into a plurality of trenches via gate insulating films, the plurality of trenches being formed such that bottoms of the trenches reach the first base layer; source layers of the first conductive type which are formed on a surface area of the second base layer so as to be adjacent to both side walls of the trench provided with the first gate electrode and one side wall of the trench provided with the second gate electrode, respectively; an emitter layer of the second conductive type which is formed on the second surface; emitter electrodes which are formed on the second base layer and the source layers; a collector electrode which is formed on the emitter layer; and first and second terminals which are electrically connected to the first and second gate electrodes, respectively.