To provide a method for producing a polyester, enabling to reduce the by-production of diethylene glycol(DEG) causing the lowering in the melting point of the polyester and improve the productivity of the polyester.

In this method for producing a polyester from an aromatic dicarboxylic acid lower alkyl ester and an aliphatic glycol by a transesterification reaction, the aromatic dicarboxylic acid lower alkyl ester is prelimiarily heated at the melting point or higher outside the reaction system, and the aliphatic glycol is also separately preliminarily heated at 60-160°C outside the reaction system. The heated raw materials are subsequently simultaneously fed into a reactor.