A polymer which has a radical polymerizable unsaturated group in a side chain and can be made a molecular design suitable for the purpose; a curable resin composition containing the polymer, which provides a cured product having high surface hardness after curing and hardly suffering from scratch; the cured product; and an article obtained by laminating the cured product are provided. The polymer (A) of the present invention is obtained by polymerizing, at least, a vinyl monomer represented by the following general formula (1) and a cyclic ether compound represented by the following general formula (2). The polymer (A) of the present invention is preferably obtained by polymerization of 1 wt % or more and 99.9 wt % or less of a vinyl monomer represented by the general formula (1), 0.1 wt % or more and 99 wt % or less of a cyclic ether compound represented by the general formula (2) and 0 wt % or more and 98.9 wt % or less of the other cationic polymerizable monomer. [wherein R1 represents an alkylene group having 2 to 8 carbon atoms, R2 represents a hydrogen atom or a methyl group, and m represents a positive integer] [wherein n represents an integer of 1 to 5].