PURPOSE: To prevent indium from diffusing to a second electrode layer and prevent a deterioration of morphology on a surface of the second electrode layer by a method wherein a high melting point metal layer of which a melting point is more than that of platinum is provided between a first metal layer and a second metal layer.

CONSTITUTION: In an ohmic electrode structure to an n+-type InGaAs ohmic contact layer 17 being a III-V compound semiconductor layer, this is that a Pt layer 22 is inserted into a laminated structure of AuGe-NiAu. thereby, it is possible to prevent In in the n+-type InGaAs ohmic contact layer 17 from diffusing excessively to an electrode surface by an alloying heat treatment, and segregation of In of an electrode surface and unequalization of alloying can be reduced. Accordingly, the morphology of the electrode surface becomes excellent, and also as sheet resistance and contact resistance of the ohmic electrode are stabilized, it is possible to enhance element performance and reliability.