To provide a manufacturing method of a MOS field-effect transistor in which such a structure is adopted that SiGe having a large lattice constant is embedded immediately below a channel and distortion is effectively introduced in a channel Si layer so that mobility of electrons or holes are drastically improved, thereby realizing high-speed operation and low power consumption. A stressor 2 composed of silicon germanium is formed in a portion in an active region that is separated by an insulating film formed on a silicon substrate, a silicon channel layer 1 composed of silicon is formed above the stressor, and a tensile stress layer 10 is formed so as to surround a gate electrode and a sidewall formed on the gate electrode.