To make it possible to form a bright surface which is good in both of reflectivity and appearance and has high texture by subjecting an aluminum wheel cast disk surface to die sinking, powder coating and under coating, then to top coating by sputtering of aluminum.

The aluminum casting is subjected to die sinking, then to degreasing and chromating treatments as pretreatments. The aluminum casting is electrostatically coated with powder coating materials of polyester or acrylic and epoxy resins and the coatings are baked for 20 minutes at, for example, 140°C. Since the surface roughness of machining is usually 20 to 50μm in Rmax, the formation of the smooth surface by the powder layer is made possible. Next, the surface is coated with the coating materials of the urethane, acrylic and epoxy resins as an under coating layer and the coatings are baked for 20 minutes at 140°C. Sputtering is then executed by an inline type magnetron supporting device. The urethane, acrylic and epoxy resins are used for the top coating and are baked for 30 minutes at 100°C.