Disclosed is a nitride semiconductor device which comprises: a semiconductor substrate (101); a nitride semiconductor layer (102) that is formed on the semiconductor substrate; a backside electrode (135) that is formed on a surface of the semiconductor substrate, said surface being on the reverse side of the surface on which the nitride semiconductor layer is formed; and a through electrode (113) that penetrates through the nitride semiconductor layer and the semiconductor substrate and is connected with the backside electrode. The semiconductor substrate has a normal region (101A) and an interfacial current blocking region (101B) that surrounds the normal region. The nitride semiconductor layer has an element region (102A) and an element isolating region (102B) that surrounds the element region. The element region is formed on the normal region, and the interfacial current blocking region contains an impurity and forms a potential barrier with respect to carriers that are generated at the interface between the nitride semiconductor layer and the semiconductor substrate.
