The present invention relates to a composition for manufacturing a carboxylic group-containing polymer and a carboxylic group-containing polymer manufactured by using the same. More particularly, the present invention relates to a composition for manufacturing a carboxylic group-containing polymer comprising an allyl monomer having a long chain of a hydrophilic part containing alkylene oxide and a side chain of a hydrophobic part containing fatty acid ester as a dispersion promoter; a vinyl group-containing unsaturated carboxylic acid; a vinyl group-containing crosslinking agent; and a radical polymerization initiator, and a carboxylic group-containing polymer manufactured by using the same wherein the polymer can be dispersed in water without stirring, its dispersion solution has low viscosity, and its neutralized viscous solution obtained by alkali neutralization has high viscosity and transparency. Therefore, the carboxylic group-containing polymer of the present invention can be effectively used in the fields of a thickener and a dispersion stabilizer for an emulsion, a suspension and the like.