PRODUCTION OF POLYESTER

PROBLEM TO BE SOLVED: To provide a method for industrially and advantageously producing a high-quality polyester by reutilizing a distilled glycol produced in each step as a part or the total amount of raw materials. SOLUTION: Terephthalic acid and a glycol are fed to esterification reactors 3 and 4 to carry out the esterification reaction and the resultant ester low polymer is then fed to polycondensation reactors 11 to 13 to conduct the polycondensation. Thereby, a polyester is produced. A distillate discharged from the polycondensation reactors 11 to 13 or esterification reactors 3 and 4 and consisting essentially of the glycol as a cooling liquid for condensing a gas produced in the esterification reaction is sprayed into a partial condenser 5. The resultant partial condensate is filtered to separate undissolved substances. The separated filtrate is subsequently reutilized as a part or the total amount of the raw materials.