A surface-treated steel sheet includes: a steel sheet; and a coated layer which is formed on one surface or both surfaces of the steel sheet and includes zinc and vanadium, wherein the coated layer has a vanadium content of 1% or higher and 20% or less and a coating weight of 3 g/m2 or higher and 40 g/m2 or less, and has a plurality of dendritic arms that are grown in a thickness direction of the steel sheet, and a ratio x/y of a content x of vanadium that is present outside the arms to a content y of vanadium that is present inside the arms is 1.1 or higher and 3.0 or less in terms of vanadium element.