Abstract: This invention provides a process to form a coated film characterized in that, after a cationically electrodeposition paint is applied on a metal-made article to be coated and is heat-cured, the surface of the resulting electrodeposition coated film is coated with an aqueous primer, which is mainly composed of such a thermoplastic polyurethane resin as is produced by subjecting a carboxyl group-containing urethane prepolymer to chain extension in the presence of an aqueous medium, and, successively, with an aqueous base paint, and, next, with a clear paint, and that the resulting three-layer coated films are heated and are thereby cured simultaneously. By this process, there can be formed a multi-layer coated film excellent in chipping-resistance, corrosion-resistance, weatherability and physical performances.