PROBLEM TO BE SOLVED: To provide a surface modification method of vulcanizate or thermoplastic elastomer capable of adding functionalities such as slidability and liquid spilling resistance economically advantageously.SOLUTION: There is provided a surface modification method targeting vulcanizate or thermoplastic elastomer as a modification target and including a process 1 for forming a polymerization initiation point A on a surface of the modification target, a process 2 for growing a copolymerized polymer chain by radical polymerizing two or more kinds of monomer starting at the polymerization initiation point A, a process 3 for forming a polymerization initiation point B on a surface of the copolymerized polymer chain and a process 4 for growing a polymer chain having small deviation of electrical charges by radical polymerizing a monomer having smaller deviation of electrical charges than the two or more kinds of monomer starting at the polymerization initiation point B.SELECTED DRAWING: None
