A surface treatment method improves the surface properties of a metal member while maintaining the metal surface texture, and a metal member is obtained by the surface treatment method. The surface-treated metal member is obtained by bringing a solution of a fluorine-based polymer into contact with a surface of an anodic oxidation coating that is formed on a surface of a metal and has not been subjected to a sealing treatment, and subjecting the anodic oxidation coating to a steam sealing treatment, the surface-treated metal member comprising a fluorine-based polymer layer having a thickness of 100 nm or less, and a composite sealed layer that is formed continuously under the fluorine-based polymer layer, the composite sealed layer having a configuration in which the fluorine-based polymer is present inside pores formed in the anodic oxidation coating.