A method for fabricating a semiconductor device includes the steps of forming a SiC film, forming trenches at a surface of the SiC film, heat-treating the SiC film with silicon supplied to the surface of the SiC film, and obtaining a plurality of macrosteps to constitute channels, at the surface of the SiC film by the step of heat-treating. Taking the length of one cycle of the trenches as L and the height of the trenches as h, a relation L=h(cot α+cot β) (where α and β are variables that satisfy the relations 0.5≦α, β≦45) holds between the length L and the height h. Consequently, the semiconductor device can be improved in property.