[Object] To provide an esterification reaction product having high water-holding properties and pigment-dispersing properties. [Solving means] The esterification reaction product according to the present invention is obtained by esterifying dipentaerythritol and a 12-hydroxystearic acid polymer and has a hydroxyl value of 20 to 70 mg KOH/g and an acid value of 3 mg KOH/g or less.