Abstract: A brazing method is provided for brazing a metallic material for brazing to another metallic material. The metallic material for brazing includes a base material portion made of copper or a copper alloy containing chrome by a predetermined amount, and a metallic film portion made of a material having a melting point lower than a heating temperature in brazing, and provided on the surface of the base material portion. The brazing method includes a step of assembling the metallic material for brazing and the another metallic material to form an assembly, a step of heating and brazing the assembly, in which the metallic film portion is melted to diffuse chrome into a surface of the metallic material for brazing, and a step of forming a chrome oxide film by using the chrome diffused into the surface of the metallic material for brazing in atmosphere after the brazing step.