Nippon Paint Co. has been granted a patent for a metal surface treatment liquid for cation electrodeposition coating which is comprised of zirconium ions, copper ions and other metal ions, and has a pH of 1.5 to 6.5, wherein the other metal ions are at least one selected from the group consisting of tin ions, indium ions, aluminum ions, niobium ions, tantalum ions, yttrium ions and cerium ions; the concentration of zirconium ions is in the range of 10 to 10,000 ppm; the concentration ratio of the copper ions to the zirconium ions is in the range of 0.005 to 1 on a mass basis; and the concentration ratio of the other metal ions to the copper ions is in the range of 0.1 to 1,000 on a mass basis; and further comprised of a hydrolysis condensate of aminosilane.
