A p+-type anode region that forms a contact of an anode electrode on a front surface of a semiconductor substrate and a p+-type starting substrate of a rear surface of the semiconductor substrate is formed on the front surface of the semiconductor substrate, whereby an up-anode type vertical diode is configured. The semiconductor substrate has a p−-type epitaxial layer stacked on the p+-type starting substrate, and a p-type transition layer in a surface layer of the p−-type epitaxial layer, facing the p+-type starting substrate. A p-type anode diffusion region is provided between a p+-type surface anode region and the p-type transition layer, and contacts the p+-type surface anode region and the p-type transition layer. A p-type impurity concentration of the p-type anode diffusion region decreases from an interface with the p+-type surface anode region toward an interface with the p-type transition layer.