To provide a water-dissipatable polyester having good hydrolysis stability and the original characteristics of polyesters.

This water-dissipatable polyester has carbonyloxy bond groups (≤80% of the bond groups of the polyester are carbonylamide bond groups) in the linear molecule structure. The polymer has an ASTM D4287 viscosity of 5P to 50P at 200°C, and the polymer comprises the reaction product of a bifunctional dicarboxylic acid comprising a dicarboxylic acid and its ester, a bifunctional reactant comprising a glycol or a mixture of the glycol with an amine, a bifunctional reactant comprising an aminoalcohol, an aminocarboxylic acid and a diamine hydroxycarboxylic acid, and a multifunctional reactant containing three to six functional groups selected from the group consisting hydroxy groups, carboxyl groups and their mixtures or its ester-forming or esteramide-forming derivative.