Disclosed is a vertical nitride semiconductor device including a conductive substrate; a semiconductor layer bonded to the conductive substrate via a second electrode; a metal layer formed on the conductive substrate; a first electrode formed on the semiconductor layer; and a bonding layer formed between the conductive substrate and the second electrode. The conductive substrate has a flange part, which extends from a side surface of the conductive substrate, on a side of the other front surface thereof. The flange part is formed in a manner in which the conductive substrate and the semiconductor layer are bonded together and then a remaining part of the conductive substrate is divided, the remaining part being formed by cutting off the semiconductor layer and part of the conductive substrate in a thickness direction so as to expose a side surface of the semiconductor layer and the side surface of the conductive substrate.