A HDTMOS includes a Si substrate, a buried oxide film and a semiconductor layer. The semiconductor layer includes an upper Si film, an epitaxially grown Si buffer layer, an epitaxially grown SiGe film, and an epitaxially grown Si film. Furthermore, the HDTMOS includes an n-type high concentration Si body region, an n− Si region, a SiGe channel region containing n-type low concentration impurities, an n-type low concentration Si cap layer, and a contact which is a conductor member for electrically connecting the gate electrode and the Si body region. The present invention extends the operation range while keeping the threshold voltage small by using, for the channel layer, a material having a smaller potential at the band edge where carriers travel than that of a material constituting the body region.