Abstract: A process for producing an aromatic polyester having an aromatic dicarboxylic acid as a main acid component and trimethylene glycol or tetramethylene glycol as a main glycol component from a starting material composed mainly of an aromatic dicarboxylic acid or its functional derivative and trimethylene glycol or tetramethylene glycol; wherein at least one organometallic catalyst selected from the group consisting of organotitanium compounds and organotin compounds and at least one promoter selected from the group consisting of organic sulfonic acids and aliphatic carboxylic acids and being capable of increasing the catalyst activity of the organometallic catalyst are added to the reaction system so that the promoter increases the catalytic activity of the organometallic catalyst, and an aromatic polyester having an increased degree of polymerization is formed at an increased rate of polymerization.