Provided are a semiconductor device comprising a semiconductor substrate, a first insulating film formed thereover, interconnects formed over the first insulating film and having copper as a main component, a second insulating film formed over the upper surface and side surfaces of each of the interconnects and over the first insulating film and having a function of suppressing or preventing copper diffusion, and a third insulating film formed over the second insulating film and having a dielectric constant lower than that of the second insulating film; and a method of manufacturing the semiconductor device. This invention makes it possible to improve dielectric breakdown strength between copper interconnects and reduce capacitance between the copper interconnects.