Rapid synthesis of aliphatic polyesters by direct polycondensation, which does not generate any wastes, is an ideal method for producing polyesters. We report a rapid, environmentally-benign, solvent-free method for synthesis of poly(butylene succinate) (PBS) and poly(lactic acid) (PLA) through microwave irradiation in the presence of tin catalyst. The microwave irradiation accelerated the polymerization rate more than 10 times compared with the conventional heating method. PBS with average molecular weight (M_w) of 29000 and PLA with M_w of 16000 were obtained within 30 minutes.