The object of the present invention is to improve the interfacial adhesion between the film with low dielectric constant and protective film, without damaging the excellent dielectric, flatness and gap-filling characteristics of the organic material of low dielectric constant, and for that purpose there is provided a wiring structure with the copper film embedded in the insulation film of the wiring layer, wherein the insulation film of the wiring layer is of a multi-layered structure with the laminated methyl silsesquioxane (MSQ) film, methylated hydrogen silsesquioxane (MHSQ) film and silicon oxide film.