The semiconductor device includes a silicon substrate having a channel region, a gate electrode formed over the channel region, buried semiconductor regions formed in a surface of the silicon substrate on both sides of the gate electrode, for applying to the surface of the silicon substrate a first stress in a first direction parallel to the surface of the silicon substrate, and stressor films formed on the silicon substrate between the channel region and the buried semiconductor regions in contact with the silicon substrate, for applying to the silicon substrate a second stress in a second direction which is opposite to the first direction.