A semiconductor device of an embodiment includes a p-type SiC impurity region containing a p-type impurity and an n-type impurity. Where the p-type impurity is an element A and the n-type impurity is an element D, the element A and the element D form a combination of Al (aluminum), Ga (gallium), or In (indium) and N (nitrogen), and/or a combination of B (boron) and P (phosphorus). The ratio of the concentration of the element D to the concentration of the element A in the above combination is higher than 0.33 but lower than 0.995, and the concentration of the element A forming part of the above combination is not lower than 1×1018 cm−3 and not higher than 1×1022 cm−3.