A doping concentration distribution in an accumulation region in a depth direction of a semiconductor substrate has a maximum portion at which a doping concentration reaches a maximum value, an upper gradient portion in which the concentration decreases from the maximum portion to a base region, and a lower gradient portion in which the concentration decreases from the maximum portion to a drift region. When a full width at half maximum determined by setting a depth position of the maximum portion as a range of impurity implantation with reference to a range-full width at half maximum characteristic according to a material of the substrate and a type of impurities contained in the accumulation region is set as a standard full width at half maximum, a full width at half maximum of the distribution in the accumulation region is 2.2 times the standard full width at half maximum or greater.