In order to improve the reliability of a semiconductor device having a fuse formed by a Damascene technique, a barrier insulating film and an inter-layer insulating film are deposited over a fourth-layer wiring and a fuse. The barrier insulating film is an insulating film for preventing the diffusion of Cu and composed of a SiCN film deposited by plasma CVD like the underlying barrier insulating film. The thickness of the barrier insulating film covering the fuse is larger than the thickness of the underlying barrier insulating film so as to improve the moisture resistance of the fuse.