The invention provides a surface modification method for perduren and thermoplastic elastomer, and the method does not use expensive self-lubricating resin, is capable of providing excellent sliding performance and durability for repetitive sliding and retains sealing performance. Perduren and thermoplastic elastomers are the modified objects of the surface modification method. The method comprises a first step of forming sulfur-containing photopolymerization points on the surface of the object to be modified and a second step of allowing monomers to undergo free radical polymerization with the sulfur-containing photopolymerization points as the starting point and the polymer chains to grow on the surface of the object to be modified.
