A surface treatment for metal, prepared by adding a cationic or nonionic, urethane, acrylic, epoxy, polyester, or polyamide resin, a resin compound represented by the general formula (I), and a compound of Zr, Ti, V, Mo, W, Mn, or Ce to water; a process for surface treatment of metallic substances; and surface-treated metallic substances: (I) [wherein R1 is -CH2-, -CH2-NH-C H2- , or -CH=N-CH2-; Y is H or a group represented by the general formula (II): (II) Z is a residue of an aromatic compound or the like; W is H or a group ( P) selected from among -CH2X, -CH2NHCH2X, and -CH=NCH2X (wherein X is OH, OR4, halogeno, -N(R5)(R6), or -N+(R7)(R8)(R9)A-) , with the proviso that the degr ee of substitution with the group (P) satisfies the relationship: (number of Ps ) / (total number of benzene rings and Zs) = 0.2 to 4.0; n is 0 to 29; and m is 0 to 10]. The surface treatment is free from chromium and can impart excellent corrosion resistance, alkali resistance and fingerprinting resistance to metallic substances.