According to some embodiments, a semiconductor device manufacturing method includes forming a sacrificial film on a material film. The method includes processing the sacrificial film, and forming a first groove in the sacrificial film having a first width and a second groove in the sacrificial film having a second width larger than the first width, the material film defining a base of the first groove and a base of the second groove. The method includes forming a catalyst layer on the sacrificial film, and on the base of the first groove and the base of the second groove. The method includes forming a first metal film having a thickness equal to or larger than half the first width and smaller than half the second width on the catalyst layer by plating. The method includes removing at least a portion of the first metal film in the second groove while leaving a portion of the first metal film in the first groove unremoved. The method includes removing the catalyst layer on the sacrificial film while leaving the catalyst layer on the base of the second groove unremoved. The method includes forming a second metal film in the second groove by the plating.