A semiconductor device comprises: a lower interconnect formed over a semiconductor substrate; an insulating film formed on the lower interconnect; a via hole penetrating the insulating film to reach the lower interconnect; a first barrier film covering bottom and side surfaces of the via hole; and a metal film filling the via hole covered with the first barrier film. A portion of the first barrier film covering a lower end of the side surface of the via hole is thicker than a portion covering the bottom surface of the via hole.