PURPOSE: To subject a Cu alloy product to novel surface treatment by polishing the product with emery, putting the product and an abrasive material in a centrifugal barrel machine, surface-preparing the product by centrifugal fluidized barrel polishing and forming a protective coating film on the surface of the product by clear coating.

CONSTITUTION: A Cu alloy product such as a spigot is polished with emery or buffed and put in a centrifugal barrel machine together with an abrasive material, e.g. composed of steel shots, a compd. and water. The product is surface-prepaired by centrifugal-fluidized barrel polishing, and a protective coating film is formed on the surface of the product by clear coating. A Cu alloy product having an original surface state can be obtd.