To provide a method for producing a rubber-reinforcing wire which is adhered to a rubber in a short time; to provide a rubber-reinforcing wire, and to provide a rubber-reinforcing wire-rubber composite using the same.

The method for producing the rubber-reinforcing wire, comprising applying a metal-plating treatment using a copper-zinc alloy plating bath not containing a cyan compound to a rubber-reinforcing wire and then applying a wire-drawing processing to the plated wire, includes surface-treating the rubber-reinforcing wire with a cobalt salt solution after the application of the wire-drawing processing. The pH of the cobalt salt solution is preferably 5.0 to 7.0, and the concentration of the cobalt salt is preferably 0.01 to 0.10 mol/L.