The method for forming wiring includes: laminating a thermosetting resin film and a metallic foil on an insulating substrate where base-layer wiring is formed, a mat surface of the metallic foil facing the resin film, pressing the film and the foil with application of heat; forming an opening in the metallic foil to expose a part of the insulating resin layer in which a via hole is to be formed; forming the via hole in the insulating resin layer by using as a mask the metallic foil; performing a desmear process of the via hole via the opening of the metallic foil; removing the metallic foil; forming an electroless-plated layer that covers the top surface of the insulating resin layer, a side surface of the via hole and a top surface of the base-layer wiring; and forming wiring including an electroplated layer on the electroless-plated layer.