A plating jig that can form a metal plating film simultaneously on both surfaces of a semiconductor wafer by one plating process. The plating jig includes a base section and a cover section that can hold a substrate to be plated, and a center section that holds the substrate between the base section and cover section; the base section, the cover section and the center section each having an annular portion having an opening at a center thereof; seal packings each having a conductive ring disposed thereon being attached to each of facing surfaces of the annular portions of the base section and the cover section; the substrate to be plated being disposed inside the opening of the center section; and the substrate to be plated being held from front and back surfaces thereof with the seal packings attached to the cover section and the center section.