A surface-treating agent for vulcanized rubber, comprising 10 to 160 parts by weight of a wax having a softening point of 40 to 160° C. and 10 to 160 parts by weight of fluororesin particles based on 100 parts by weight of the total amount of isocyanate group-containing 1,2-polybutadiene and an OH group-containing fluororesin composition that has the following formulation: a copolymer [I] of (A) a perfluoroalkylalkyl (meth)acrylate and (B) a hydroxyl group-containing (meth)acrylate, a polymer [II] of an acrylic acid alkyl ester, a polymer [III] of a fluorinated olefin, and a curing agent [IV]; wherein the weight ratio of the isocyanate group-containing 1,2-polybutadiene and the OH group-containing fluororesin composition is 50:50 to 95:5.