A semiconductor device including a first transistor of a first conductivity type provided on a first active region of a semiconductor region, and a second transistor of a second conductivity type provided on a second active region of the semiconductor region. The first transistor includes a first gate insulating film and a first gate electrode, the first gate insulating film contains a high-k material and a first metal, and the first gate electrode includes a lower conductive film, a first conductive film and a first silicon film. The second transistor includes a second gate insulating film and a second gate electrode, the second gate insulating film contains a high-k material and a second metal, and the second gate electrode includes a second conductive film made of the same material as the first conductive film, and a second silicon film.