A main semiconductor device element is a vertical MOSFET with a trench gate structure, containing silicon carbide as a semiconductor material, and having first and second p+-type regions that mitigate electric field applied to bottoms of trenches. The first p+-type regions are provided separate from the p-type base regions and face the bottoms of the trenches in a depth direction. The first p+-type regions are disposed at an interval that is at most 1.0 μm, in a first direction that is a direction in which gate electrodes extend. The second p+-type regions are provided between adjacent trenches of the trenches, separate from the first p+-type regions and the trenches, and in contact with the p-type base regions. In the first direction that is the direction in which the trenches, the second p+-type regions extend in a linear shape having a length that is substantially equal to that of the trenches.