There is disclosed a semiconductor device comprising an insulating film which is provided in at least one layer above a substrate and whose relative dielectric constant is 3.4 or less, at least one conductive layer provided in the insulating film, at least one conductive plug which is formed in the insulating film and which is electrically connected to the conductive layer to form a conduction path, at least one reinforcing material which is provided under at least the conductive layer and whose Young's modulus is 30 GPa or more, and at least one first reinforcing plug which is connected to the conductive layer and which is formed in contact with the reinforcing material.