Abstract: The present invention provides a process for surface treatment in which the surface of aluminium or its alloy can be put in a desired color and the improved wear resistance and corrosion resistance can be obtained. Anodic oxidation coatings obtained by conventional alumite treatment is porous and thus is small in wear resistance and in corrosion resistance and is insufficient in durability of coloring. The process of the present invention is characterized in that the process comprises the steps of: forming anodic oxidation coatings by conventional method on the surface of the aluminium or its alloy, thereafter applying an alternating voltage of 10 V.about.30 V within a sulfate solution or nitrate solution of a desired metal to a member on which said anodic oxidation coatings was formed by the above step, whereby said metal is electrolytically impregnated into said anodic oxidation coatings.