To provide a method for producing a polymer, which contains: bringing an intermediate polymer, which has been obtained through ring-opening polymerization of a ring-opening polymerizable monomer, into contact with, and melting the intermediate polymer in a compressive fluid having a density of 230 kg/m3 or greater, at temperature lower than a melting point of the intermediate polymer, at a ratio of 0.05 to 10, to dissolve a low-molecular-weight compound contained in the intermediate polymer in the compressive fluid, to thereby extract the low-molecular-weight compound, wherein the ratio is a ratio of a mass of the intermediate polymer to a mass of the compressive fluid.