To prevent a crack from recurring while adhesion is excellent, and the crack can be covered by a method wherein, after applying a base coating material which contains a hydrolyzable silyl group by using a vinyl series copolymer as a main binding material, a topcoating wherein an elongation at a specific temperature by using the vinyl series copolymer as the main binding material is at least a specific value, is applied.

A base coating material contains a hydrolyzable silyl group by using a vinyl series copolymer as a main binding material, and displays excellent adhesion to an inorganic series coating film. A topcoating has at least 5% elongation at 20°C by using the vinyl series copolymer as the main binding material, can cover a crack of the inorganic series coating film, does not allow the crack to recur after repairing, and can add beauty. As the main binding material, that in which an acrylic series monomer is polymerized, that in which a silicon-containing vinyl series monomer is copolymerized with another vinyl series monomer, that which is copolymerized with a fluorine-containing vinyl series monomer or the like can be used.