To provide a method for manufacturing a semiconductor device for efficiently applying a tensile stress to the channel region of an NMOS while sufficiently protecting a PMOS when using an SMT technique.

The method for manufacturing the semiconductor device containing the NMOS and the PMOS includes (a) the process forming a protective film 9 on approximately whole top face of a semiconductor substrate 1. The method for manufacturing the semiconductor device further includes (b) the process relatively thinning the film thickness of the protective film 9 on the NMOS region Sn and relatively thickening it on the PMOS region Sp by forming a resist film on the protective film 9 so as to expose the NMOS region Sn and etching the protective film 9 on the NMOS region Sn up to a prescribed thickness. The manufacturing method further includes (c) the process forming the insulating film on the protective film 9 so as to coat the NMOS region Sn and (d) the process thermally treating the insulating film and applying the tensile stress to the NMOS region Sn.