A semiconductor device includes semiconductor layers of a first conductivity-type and a second conductivity-type stacked on a silicon carbide semiconductor and having differing impurity concentrations. Trenches disposed penetrating the semiconductor layer of the second conductivity-type form a planar striped pattern; and a gate electrode is disposed therein through a gate insulation film. First and second semiconductor regions respectively of the first and the second conductivity-types have impurity concentrations exceeding that of the semiconductor layer of the second conductivity-type and are selectively disposed therein. The depth of the second semiconductor region exceeds that of the semiconductor layer of the second conductivity-type, but not that of the trenches. The second semiconductor region is arranged at given intervals along the length of the trenches. In the silicon carbide semiconductor below the trench bottoms, a third semiconductor region of the second conductivity-type and having a floating potential is disposed covering the trench bottoms.