A sacrifice positive electrode layer is formed conveniently, efficiently, and accurately on the surface of a refrigerant distributor having a complicated shape. Further, during the formation of the sacrifice positive electrode layer, the strength in the surroundings of joined parts is prevented from being lowered by excessive heating. Included are: an applying step of applying flux to remove an aluminum oxide to a surface of a plurality of outflow sections and a distributing section; an alloy disposing step of disposing a zinc-containing aluminum-silicon alloy on the surface to which the flux is applied; a forming step of forming the sacrifice positive electrode layer on the surface by heating the disposed zinc-containing aluminum-silicon alloy; a brazing material disposing step of inserting a plurality of outflow pipes into the plurality of outflow sections, respectively, and disposing an aluminum-silicon alloy brazing material on the surface of the outflow sections; and a brazing step of brazing the plurality of outflow sections with the plurality of outflow pipes, respectively, by heating the aluminum-silicon alloy brazing material.