A method for surface-modifying a rubber vulcanizate or a thermoplastic elastomer as a target for modification, the method comprising: step 1 of forming polymerization initiation points on a surface of the modification target, wherein the step 1 comprises adsorbing a photopolymerization initiator onto a surface of the modification target to form polymerization initiation points from the photopolymerization initiator on the surface; and step 2 of radically polymerizing a non-functional monomer, starting from the polymerization initiation points, to form non-functional polymer chains, and then radically polymerizing a fluoropolyether segment-containing functional monomer on the resultant non-functional polymer chains to form functional polymer chains while extending the polymer chains, wherein the non-functional monomer is at least one selected from the group consisting of acrylic acid, acrylic acid esters, acrylamide, dimethylacrylamide, diethylacrylamide, isopropylacrylamide, hydroxyacrylamide, acryloylmorpholine, acrylic acid alkali metal salts, acrylic acid amine salts, methacrylic acid, methacrylic acid esters, methacrylamide, methacrylic acid alkali metal salts, methacrylic acid amine salts, and acrylonitrile, characterized in that the fluoropolyether segment in the fluoropolyether segment-containing functional monomer is: (i) a perfluoropolyether segment comprising at least one of the following units to:: -(CF 2 O) a -,: -(CF 2 CF 2 O) b -,: -(CF 2 CF 2 CF 2 O) c -, and: -(CF(CF 3)CF 2 O) d - wherein a, b, c, and d each represent 0 or a positive integer and satisfy the relation: 2 ≤ a + b + c + d ≤ 200, or (ii) a monomer represented by the following formula: wherein R 101 represents a methyl group, an ethyl group, a hydrogen atom, a fluorine atom, a chlorine atom, or a bromine atom; m 101 represents an integer of 0 to 5; X 101 represents a hydrogen atom or a fluorine atom; and the fluoropolyether segment is a perfluoropolyether segment comprising at least one of the following units to:: -(CF 2 O) a -,: -(CF 2 CF 2 O) b -,: -(CF 2 CF 2 CF 2 O) c -, and: -(CF(CF 3)CF 2 O) d - wherein a, b, c, and d each represent 0 or a positive integer and satisfy the relation: 2 ≤ a + b + c + d ≤ 200, or (iii) a monomer represented by the following formula: wherein n 102 represents an integer of 0 to 100; and X 102 represents H or F. step 1 of forming polymerization initiation points on a surface of the modification target, wherein the step 1 comprises adsorbing a photopolymerization initiator onto a surface of the modification target to form polymerization initiation points from the photopolymerization initiator on the surface; and step 2 of radically polymerizing a non-functional monomer, starting from the polymerization initiation points, to form non-functional polymer chains, and then radically polymerizing a fluoropolyether segment-containing functional monomer on the resultant non-functional polymer chains to form functional polymer chains while extending the polymer chains, (i) a perfluoropolyether segment comprising at least one of the following units to:: -(CF 2 O) a -,: -(CF 2 CF 2 O) b -,: -(CF 2 CF 2 CF 2 O) c -, and: -(CF(CF 3)CF 2 O) d - wherein a, b, c, and d each represent 0 or a positive integer and satisfy the relation: 2 ≤ a + b + c + d ≤ 200, or (ii) a monomer represented by the following formula: wherein R 101 represents a methyl group, an ethyl group, a hydrogen atom, a fluorine atom, a chlorine atom, or a bromine atom; m 101 represents an integer of 0 to 5; X 101 represents a hydrogen atom or a fluorine atom; and the fluoropolyether segment is a perfluoropolyether segment comprising at least one of the following units to:: -(CF 2 O) a -,: -(CF 2 CF 2 O) b -,: -(CF 2 CF 2 CF 2 O) c -, and: -(CF(CF 3)CF 2 O) d - wherein a, b, c, and d each represent 0 or a positive integer and satisfy the relation: 2 ≤ a + b + c + d ≤ 200, or (iii) a monomer represented by the following formula: wherein n 102 represents an integer of 0 to 100; and X 102 represents H or F.