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 .