A rubber composition is provided for coating a steel wire material having initial adhesion strength and water resistant adhesion strength with respect to a steel wire material at or above conventional levels, the rubber composition being compounded with a compound derived from a natural product. Specifically a rubber composition for coating a steel wire material is compounded with from 0.05 to 10 parts by weight of a salt compound per 100 parts by weight of a diene rubber, the salt compound including a dicarboxylic acid derived from a natural product and an amine of a decarboxylated amino acid derived from a natural product.