<p>Disclosed is a method for the purification of a cyclic ester which comprises the steps of: mixing a co-effluent of a cyclic ester produced by the depolymerization with heating of a hydroxycarboxylic acid oligomer in the presence of a depolymerization solvent and the depolymerization solvent with an organic solvent for washing having compatibility with the depolymerization solvent and a lower boiling point than that of the cyclic ester; subjecting the resulting mixed solution to the liquid-liquid separation into an organic solvent phase containing the depolymerization solvent and a cyclic ester phase containing the organic solvent; evaporating the organic solvent from the cyclic ester phase containing the organic solvent to collect the cyclic ester having a reduced amount of the depolymerization solvent. The method enables to collect the cyclic ester in a purified form with high thermal efficiency, purification efficiency and handling property from the co-effluent produced from a depolymerization system containing the depolymerization solvent and the cyclic ester produced by the depolymerization with heating of the hydroxycarboxylic acid oligomer in the presence of the depolymerization solvent.</p>
