Abstract: A zinc-nickel alloy plating solution in an aqueous solution comprising, as represented in terms of ions, 4-30 g/liter of zinc and 0.05-4 g/liter of nickel, together with 50-220 g/liter of an alkali hydroxide, 4-110 g/liter of a complexing agent, 0.1-10 g/liter of a primary brightener, 0.01-0.2 g/liter of a booster brightener and preferably, further, 0.01-0.05 g/liter of a tertiary brightener. The primary brightener is at least one selected from the reaction products of amines such as ethylenediamine or its methyl-substituted derivatives, propylenediamine or its methyl-substituted derivatives, diethylenetriamine or its methyl-substituted derivatives, and the like with epihalohydrin. The booster brightener is at least one selected from aromatic aldehydes such as anisaldehyde, vanillin, heliotropin, veratraldehyde, and the like. The tertiary brightener is at least one selected from tellurium oxide, tellurous acid or its salts, or telluric acid or its salt.