In order to prevent a rise in resistance due to oxidation of copper wiring and diffusion of copper, a semiconductor device is provided which contains a wire protective film 1 covering the top of the copper wiring 2 formed in the insulation film and a barrier film surrounding the side and bottom of the copper wiring. The wire protective film and/or barrier film is formed with a cobalt alloy film containing (1) cobalt, (2) at least one of chromium, molybdenum, tungsten, rhenium, thallium and phosphorus, and (3) boron.