The thickness of an insulating film, which will serve as an offset spacer film and is formed in an offset monitor region, is managed as the thickness of an offset spacer film formed over the side wall surface of a gate electrode of an SOTB transistor STR, etc. When the measured thickness is within the tolerance of a standard thickness, standard implantation energy and a standard dose amount are set. When the measured thickness is smaller than the standard thickness, implantation energy and a dose amount, which are respectively lower than the standard values thereof, are set. When the measured thickness is larger than the standard thickness, implantation energy and a dose amount, which are respectively higher than the standard values thereof, are set.