The present invention provides a semiconductor device including (a) a drift region of a first-conductivity-type, (b) a base region of a second-conductivity-type, (c) a plurality of trench portions arranged next to each other in a predetermined arrangement direction on the upper surface of the semiconductor substrate, (d) an emitter region of a first-conductivity-type which has a higher doping concentration than the drift region, (e) an accumulation region of a first-conductivity-type which has a higher doping concentration than the drift region, and (f) a second-conductivity-type region of a second-conductivity-type which has a higher doping concentration than the base region, wherein the accumulation region and the second-conductivity-type region are provided between the base region and the drift region in a non-channel mesa portion that does not have the emitter region provided therein and that is of mesa portions between adjacent ones of the plurality of trench portions.