It is aimed to realize both of reserving a channel formation region and suppressing a latch-up. A semiconductor device is provided, including: a semiconductor substrate; a plurality of trench portions provided at a front surface side of the semiconductor substrate, each of which has a portion extending in an extending direction; and a first conductivity-type emitter region and a second conductivity-type contact region provided between adjacent two trench portions and exposed on a front surface of the semiconductor substrate alternately in the extending direction, wherein on the front surface of the semiconductor substrate, a length of the emitter region at a central position between the two trench portions is shorter than a length of the emitter region at portions contacting the trench portions, and on the front surface of the semiconductor substrate, at least a part of a boundary of the emitter region has a curved shape.