A discharge channel and a non-discharge channel are formed to have a similar shape, that is, to include extension portions and raise-and-cut portions continuing from end portions of both the extension portions, respectively. Then, imparting of a catalyst, washing of an unnecessary catalyst, plating, and the like are performed on a target surface, as a plating step. In an embodiment, an electrode clearance groove is formed after the plating step. Since channel grooves for the discharge channel and the non-discharge channel have a similar shape, it is possible to cause a water flow to uniformly flow in the channels when washing is performed, and thus to avoid an occurrence of a situation in which a lump is formed in the channel groove by plating.