A semiconductor device includes: a semiconductor substrate having a p-MOS region; an element isolation region formed in a surface portion of the semiconductor substrate and defining p-MOS active regions in the p-MOS region; a p-MOS gate electrode structure formed above the semiconductor substrate, traversing the p-MOS active region and defining a p-MOS channel region under the p-MOS gate electrode structure; a compressive stress film selectively formed above the p-MOS active region and covering the p-MOS gate electrode structure; and a stress released region selectively formed above the element isolation region in the p-MOS region and releasing stress in the compressive stress film, wherein a compressive stress along the gate length direction and a tensile stress along the gate width direction are exerted on the p-MOS channel region. The performance of the semiconductor device can be improved by controlling the stress separately for the active region and element isolation region.