PURPOSE: To improve a reverse withstand voltage and a responding speed by forming another Schottky barrier diode between a guard ring region and a Schottky barrier electrode reversely to a P-N junction diode formed between the ring region and a semiconductor layer.

CONSTITUTION: A forward Schottky barrier diode D1 is formed in a passage of a Schottky barrier electrode 26, an epitaxial layer 22, a semiconductor substrate 21 and an ohmic electrode 27. A reverse Schottky barrier diode D2 is formed in a passage of the electrode 26 and a guard ring region 25. A forward diode D3 is formed in a passage of the region 25 and the layer 22. Accordingly, a high reverse withstand voltage can be realized by the diode D3 for forward and reverse directions of the diode D1, and since a forward current of the diode D3 does not almost flow in a forward direction by the diode D2, a responding speed is raised.