A semiconductor device of an embodiment includes: an n-type first SiC epitaxial layer; a p-type second SiC epitaxial layer on the first SiC epitaxial layer containing a p-type impurity and an n-type impurity, the p-type impurity being an element A, the n-type impurity being an element D, the element A and the element D forming a combination of Al, Ga, or In and N, and/or a combination of B and P, the ratio of the concentration of the element D to the element A being higher than 0.33 but lower than 1.0; a surface region at the surface of the second SiC epitaxial layer containing the element A at a lower concentration than in the second SiC epitaxial layer, the ratio being higher than in the second SiC epitaxial layer; n-type first and second SiC regions; a gate insulating film; a gate electrode; a first electrode; and a second electrode.