PROBLEM TO BE SOLVED: To provide a comb type copolymer of a methacrylic acid ester having thiocarbonate and a sulfide skeleton as a material improving the refractive index and UV curability, and to provide a method for producing the copolymer.SOLUTION: A polymer represented by formula (I) is provided. [In formula (I), Rrepresents a hydrogen atom, a fluorine atom, a methyl group, a cyano group or a methoxy group; and n represents an integer of 1 or more].