According to some embodiments, a semiconductor device includes a substrate and an insulating film that is provided on the substrate. The device further includes a contact plug which includes a barrier metal layer provided in the insulating film, and a plug material layer provided in the insulating film, the barrier metal layer disposed between the plug material layer and the insulating film. The barrier metal layer includes at least a first layer including a first metal element and nitrogen, and a second layer including a second metal element different from the first metal element, and nitrogen.