the present invention provides a process for producing polyhydroxycarboxylic acids which comprises subjecting at least one hydroxycarboxylic acid or oligomer thereof to polycondensation in the presence of an alkali metal compound , an alkaline earth metal compound , or a compound of a metal of group iiib of the periodic table . the polyhydroxycarboxylic acids obtained by the process have a weight - average molecular weight of 30 , 000 or above and are useful as biodegradable plastics for food - wrapping films , drug delivery systems , etc .