Disclosed is a semiconductor device having a highly reliable wiring structure wherein adhesion between a dielectric thin film and a conductor layer is improved. Specifically disclosed is a method for manufacturing a semiconductor device comprising a step wherein a reactive plasma is supplied to the surface of a dielectric thin film wherein many pores are arranged around the skeleton mainly containing Si-O bonds for pretreating the surface, and a step for forming a conductive film on the thus-pretreated dielectric thin film surface by sputtering. This method is characterized by having a step for bringing a gas containing at least one of tetramethylcyclotetrasiloxane (TMCTS), hexamethylsilazane (HMDS), and trimethylchlorosilane (TMCS) molecules into contact with the dielectric thin film surface before the pretreatment step.