One embodiment of a semiconductor device includes: a silicon carbide substrate including first and second principal surfaces; a first-conductive-type silicon carbide layer on the first principal surface; a second-conductive-type first silicon carbide region at a surface of the first silicon carbide layer; a first-conductive-type second silicon carbide region at the surface of the first silicon carbide region; a second-conductive-type third silicon carbide region at the surface of the first silicon carbide region; a second-conductive-type fourth silicon carbide region formed between the first silicon carbide region and the second silicon carbide region, and having an impurity concentration higher than that of the first silicon carbide region; a gate insulator; a gate electrode formed on the gate insulator; an inter-layer insulator; a first electrode connected to the second silicon carbide region and the third silicon carbide region; and a second electrode on the second principal surface.