Abstract: A process for producing a joint structure of a steel sheet and an aluminum sheet, in which the steel sheet and the aluminum sheet are joined to each other so as to be electrically connected to each other. The process is characterized by comprising a step of forming at least one resin coating film in a thickness of 0.1 to 5.0 ?m on a contact surface on the steel sheet side, wherein the resin is selected from the group consisting of a polyolefin resin, a polyurethane resin and an epoxy resin.

Abstract: Disclosed is a surface-treated metal material which includes a metallic base including a steel or aluminum material; and an anti-corrosive layer present covering at least one surface of the metallic base. The anti-corrosive layer contains 0.001 to 1 g/m2 of one or more substances selected from the group consisting of benzoic acid salts, glutamic acid salts, anisidines, glycine, and quinolinols. The benzoic acid salts and/or glutamic acid salts are preferably chosen from potassium salt, sodium salt and ammonium salt. Also disclosed is a joined article of dissimilar materials including the surface-treated metal material as at least one of the materials. The surface-treated metal material includes, as the base metal, a steel or aluminum material and is thereby effectively and inexpensively protected from galvanic corrosion without performing electrical insulation or complete atmospheric isolation.