a preparation process of polyhydroxycarboxylic acid comprising conducting dehydration polycondensation of hydroxycarboxylic acid or an oligomer of the same in a reaction mixture containing said hydroxycarboxylic acid or the oligomer of the same and an organic solvent substantially in the absence of water to give polyhydroxycarboxylic acid having an weight average molecular weight of 50 , 000 or more , successively mixing the reaction mixture containing said polyhydroxycarboxylic acid with at least one binder selected from the group consisting of polyisocyanate compound , polybasic acid anhydride , cyclic imino ester , cyclic imino ether , aromatic hydroxycarboxylic acid , polyamino compound , polyhydric alcohol , epoxy compound , polyfunctional aziridine compound , lactam , lactone , and diethylene glycol bischloroforate , and reacting to obtain polyhydroxycarboxylic acid having a weight average molecular weight of 100 , 000 or more the polyhydroxycarboxylic acid which is obtained by the process has a weight average molecular weight of 100 , 000 or more , has satisfactory mechanical strength in the form of molded articles and is useful as a degradable polymer for substituting medical materials and general purpose resins .