To obtain an unsaturated polyester resin-based coating material excellent in surface hardness, surface smoothness and scratching resistance without harming weather resistance and processing properties, and useful for a construction material, etc., by incorporating an unsaturated polyester resin and wollastonite in it.

This coating material contains (A) an unsaturated polyester resin obtained by mixing an unsaturated polyester produced by a polycondensation reaction of an unsaturated polybasic carboxylic acid such as maleic anhydride, etc., with a polyhydric alcohol such as propylene glycol, etc., with a vinyl compound such as styrene and cross-linking by a polymerization by using a peroxide catalyst, with (B) preferably 10-40 wt.% (based on the total amount of the coating material) wollastonite having e.g. 20-50 μm mean fiber length, 0.05-5 μm mean fiber diameter and 8-100 aspect ratio. Further, it is preferable to apply the coating material on the whole surface or a part of the surface of the metal plate having a metallic layer containing zinc, aluminum or an alloy containing one kind of them and baking for producing a coated metal plate.