To make the resistance component of a channel region comparable to that of a silicon device, to enable the semiconductor device to be manufactured according to the manufacturing process of a silicon device, and make the variations in the threshold of the semiconductor device comparable to those of a silicon device, in a power semiconductor device whose drift region consisting of a wide band-gap semiconductor, such as gallium nitride.

A first semiconductor layer 3 of gallium nitride is laminated on a support substrate 2 of silicon, and a second semiconductor layer 4 of silicon is laminated further thereon. A surface structure of the semiconductor device is fabricated in this second semiconductor layer 4 by using existing advanced processing technologies, such as microfabrication technology for silicon, etc. Further, a high breakdown voltage structure, wherein the second semiconductor layer 4 is removed to expose the first semiconductor layer 3, is provided in the peripheral portion of the chip.