forming a monocrystal SiGe layer on a monocrystal Si layer formed on an insulating film; and

thermal-oxidizing the monocrystal Si layer and the SiGe layer at an initial oxidation temperature at a first stage and at a final oxidation temperature lower than the initial oxidation temperature at a final stage to form a Si oxide film on the Si layer and the SiGe layer on a side opposite to the insulating film and to form a monocrystal Ge layer having a compressive strain, wherein the thermal-oxidizing is performed at a temperature not more than a melting temperature of the SiGe layer, and by setting the initial oxidation temperature at a value exceeding 1000° C. and a final oxidation temperature at not more than 900° C. while decreasing the heating temperature gradually.