A substrate with a through-hole is immersed in a plating solution in a plating tank. A pair of anodes are disposed in the plating solution in the plating tank in facing relation to face and reverse sides, respectively, of the substrate in the plating solution. A plurality of plating processes are performed on the face and reverse sides by supplying pulsed currents respectively between the face side of the substrate and one of the anodes which faces the face side of the substrate, and between the reverse side of the substrate and the other anode which faces the reverse side of the substrate. A reverse electrolyzing process is performed on the face and reverse sides between adjacent plating processes by supplying currents in an opposite direction to the pulsed currents respectively between the face side of the substrate and one of the anodes, and between the reverse side of the substrate and the other anode.