A polyester resin having low-temperature (80-240° C.) fluidity, storage stability, and achieving both dispersibility and grindability, where the polyester resin includes, in reacted form: a polyhydric alcohol; a polycarboxylic acid; a sulfonate component, which is a bis(2-hydroxyethyl)isophthalate sulfonic acid salt; and a hetero alicyclic skeleton, which can be a monomer of formula (1) and/or formula (2): where X is O, S, or NH and R1 to R4 are functional groups. Also, a method for producing the polyester resin by polymerizing a mixture containing the polyhydric alcohol, the polycarboxylic acid, the sulfonate component and the hetero alicyclic skeleton component having formula (1) and/or (2).