Disclosed is a semiconductor device wherein device characteristics are improved by applying a strong stress to a channel region. The semiconductor device includes a semiconductor substrate, a gate insulating film formed over a first plane of the semiconductor substrate, a gate electrode formed over the gate insulating film, a gate sidewall insulating film formed over the sidewall of the gate electrode, source/drain diffusion layer regions into which impurities are implanted, the source/drain diffusion layer regions being adjacent to a channel region formed in the semiconductor substrate below the gate electrode, and a stress applying film formed over the source/drain diffusion layer regions except over the upper part of the gate electrode; and recesses or protrusions are formed in the region where the source/drain diffusion layer regions are formed over the first plane of the semiconductor substrate.