In a trench deeper than a thickness of a p-type base layer and configured by a first trench and a second trench, a second trench positioned at a lower portion is configured by a third trench and a fourth trench. A width of the second trench along an X direction is expanded more than the first trench positioned above the second trench. Along the X direction, the extent to which the second trench is expanded differs for the third trench and the fourth trench. Thus, a width of the lower portion of the trench differs along a Y direction, enabling reduced gate capacitance compared to uniform expansion along a transverse direction of the trench. Further, ON voltage may be reduced and switching capability may be improved.