The performance of the semiconductor device which formed the metal silicide layer in the salicide process is improved. An element isolation region is formed in a semiconductor substrate by the STI method, a gate insulating film is formed, a gate electrode is formed, n+ type semiconductor region and p+ type semiconductor region for source/drains are formed, a metallic film is formed on a semiconductor substrate, and a barrier film is formed on a metallic film. And after forming the metal silicide layer to which a metallic film, and a gate electrode, n+ type semiconductor region and p+ type semiconductor region are made to react by performing first heat treatment, a barrier film, and an unreacted metallic film are removed, and the metal silicide layer is left. An element isolation region makes compressive stress act on a semiconductor substrate. A barrier film is a film which makes a semiconductor substrate generate tensile stress, and the metal silicide layer which consists of mono-silicide MSi of metallic element M which forms a metallic film is formed in the first heat treatment.