Trenches and n+ high impurity concentration regions are formed in a first principal surface side of a silicon carbide semiconductor substrate. In the n+ high impurity concentration regions, third n-type regions that respectively surround first p+ base regions contacting a p-type base layer and have a higher impurity concentration than the n+ high impurity concentration regions, as well as fourth n-type regions that respectively surround second p+ base regions formed at the bottoms of the trenches and also have a higher impurity concentration than the n+ high impurity concentration regions, are formed.