The present invention is directed to an object of the present invention is to achieve both of the characteristics of the two that whiteness improvement of the particle surface color (absorption capacity improvement, reduction of residual monomer and water-soluble component) and water absorption properties. For this purpose, the particulate water-absorbing agent of the present invention, there is provided a particulate water-absorbing agent as a main component polyacrylic acid (salt), b value in the Hunter Lab color system surface of the particles in -5 10 Yes, 3 and the following formula 1 Equation 1 GEX = (GVs + 17) / Ln (water soluble content) Equation 3 CPI = (GEX / residual monomer content) × 100 (Natural logarithm of the water soluble content GVs:: absorption capacity without load, Ln (water soluble content)) And is characterized in that the crosslinked product quality index which is defined by (CPI) is 1 to 100.本発明は、優れた吸水特性(吸水倍率向上、水可溶分および残存モノマーの低減)と粒子表面色の白度向上という二つの特性の両立を実現することを目的としている。この目的にために、本発明の粒子状吸水剤は、ポリアクリル酸(塩)を主成分とする粒子状吸水剤であって、粒子のハンターLab表面色系におけるb値が-5~10であり、下記式1及び3式1;GEX=(GVs+17)/Ln(水可溶分量)式3;CPI=(GEX/残存モノマー量)×100(GVs:無加圧下吸収倍率,Ln(水可溶分量):水可溶分量の自然対数)により規定される架橋体特性指数(CPI)が1~100であることを特徴としている。
