Abstract: An object of the present invention is to provide: succinic anhydride that little becomes colored in a melted state; a production process for such succinic anhydride; and a production process for a polyester, by which there can be obtained a polyester of an extremely reduced color. As means of achieving such an object, the succinic anhydride is characterized by having a &ggr;-butyrolactone content of not more than 800 ppm and a dilactone content of not more than 500 ppm. The production process for the succinic anhydride is characterized in that: the hydrogenation reaction is carried out in the presence of a catalyst in the temperature range of 120 to 160° C. under a hydrogen pressure of 0.1 to 2.0 MPa; and the distillation is carried out in such a manner that the bottom temperature will be within the temperature range of 125 to 200° C. by reducing the pressure. The production process for the polyester is characterized in that the aforementioned succinic anhydride is used as an acid component.

Abstract: A method for producing an aliphatic polyester having a biodegradability and a higher melting point than conventional aliphatic polyester by suppressing a volatile component generated by side reaction or decomposition reaction with industrially good efficiency and economically in a relatively short period of time, the method enabling a polymerization at vacuum which permits a use of general vacuum pump. The aliphatic polyester can be obtained, for example, by a ring-opening copolymerization of a cyclic acid anhydride with a cyclic ether in a presence of a zirconium compound. The aliphatic polyester also can be obtained by performing a polymerization of raw materials of the aliphatic polyester so as to have a degree of viscosity in the range of 10-10,000 poise when 0.1-30 hours elapsed after the reaction started at reaction temperature of the reaction system under conditions of reaction temperature in the range of 180.degree. C. to 280.degree. C. and reaction pressure in the range of 0.3 mmHg to 3.0 mmHg.