Metal Surface Treatment Agent, Metal Surface Treatment Method, and Metal Material

The present invention addresses a problem of providing, for example, a metal surface treatment agent capable of forming a coating film that exhibits good corrosion resistance at edges, such as cut portions, of a coated metal material. The problem is solved by a metal surface treatment agent comprising: an ion (A) containing at least one kind of metal selected from zirconium, titanium and hafnium at a metal-equivalent molar concentration of 0.1 mmol/L or higher; and an aqueous urethane resin (B) having a weight-average molecular weight of 50,000 or higher at a solid mass concentration of 0.5 to 10 g/L, in which the ratio of a solid mass (BM) of the resin (B) to a metal-equivalent mass (AM) of the ion (A), [BM/AM], is 0.7 or higher.