A semiconductor device including an n-channel MISFET including source/drain regions 38 formed in a semiconductor substrate 10 with a channel region between them, and a gate electrode 44 of a metal silicide formed over the channel region with a gate insulating film 12 interposed therebetween; and an insulating film 46 formed over the gate electrode 44 from side walls of the gate electrode 44 to an upper surface of the gate electrode 44, having a tensile stress from 1.0 to 2.0 GPa and applying the tensile stress to the channel region.