A semiconductor device includes: a semiconductor substrate; a p-channel field effect transistor formed in a first region of the semiconductor substrate; an n-channel field effect transistor formed in a second region of the semiconductor substrate; a compressive stress film with a compressive stress generated inside, the compressive stress film covering the first region; a tensile stress film with a tensile stress generated inside, the tensile stress film covering the second region; and a buffer film located between the p-channel field effect transistor and the n-channel field effect transistor on the semiconductor substrate, the magnitude of internal stress of the buffer film being smaller than the magnitude of the compressive stress of the compressive stress film and the magnitude of the tensile stress of the tensile stress film.