The invention provides a process for producing a carboxyl-containing polymer composition that allows the possibility of obtaining a carboxyl-containing polymer composition which exhibits excellent dispersibility in water or the like, has a viscosity increasing to a lower degree compared to the viscosity of a neutralized viscous liquid using an additive-free carboxyl-containing polymer, and has a high degree of transparency in a neutralized viscous liquid thereof. A carboxyl-containing polymer composition is obtained by polymerizing a monomer containing an α,β-unsaturated carboxylic acid as a main component in a presence of a polyol (iso)stearic acid ester. A polyol in the polyol (iso)stearic acid ester is a polyol selected from a specific group, and the polyol (iso)stearic acid ester is used in the polymerization in an amount of 0.2 to 7 parts by mass based on 100 parts by mass of the α,β-unsaturated carboxylic acid.