To provide a method for producing a reinforcing cord, capable of improving water resistance and oil resistance by preventing water, nor an oil, from penetrating into the reinforcing cord.

This method for producing the reinforcing cord comprises forming a cover layer made of a polymer material on a side surface of a reinforcing fiber bundle by extrusion molding. It is preferable that a thermoplastic elastomer, rubber, or a mixed material thereof is used as the polymer material. Further, it is preferable that a primary coat layer is formed on the reinforcing fiber bundle, by preliminarily impregnating the bundle with a rubber latex, etc., and drying the bundle.