The present invention aims to provide a surface modification method of a vulcanized rubber or a thermoplastic elastomer, which can be economically and advantageously given functionalities, such as sliding performance, biocompatibility, etc., according to uses. The present invention relates to the surface modification method of taking the vulcanized rubber or the thermoplastic elastomer as a surface modification object, and the method comprises a step 1 of forming photopolymerization point on the surface of the surface modification object, and a step 2 of growing a non-functionality polymeric chain via a free radical polymerization non-functionality monomer by taking the above photopolymerization point as a starting point, and further growing a functionality polymeric chain via a free radical polymerization functionality monomer.
