PROBLEM TO BE SOLVED: To provide a water-absorbent resin having a high diffusibility and capable of improving an absorption performance under a load, in the case where it is used in an absorber, and an absorbent article using an absorber containing the water-absorbent resin.SOLUTION: A water-absorbing resin of the invention is the water-absorbing resin which is obtained by polymerizing a water-soluble ethylenic unsaturation monomer under the presence of an internal crosslinking agent and by performing an after cross linking of the polymerized monomer with an after-crosslinking agent, wherein a physiologic saline absorption performance under a load of 4.14 kPa is 16 mL/g or higher, wherein the mass ratio of particles of 150 to 850 &mu；m occupying said water-absorptive resin entirety is 85 mass % or more, wherein the mass ratio of the particles of 300 to 400 &mu；m is 20 mass% or more, and wherein the absorption capacity elasticity index expressed by the following formula (I) is 68000 or more. Absorption Capacity Elasticity Index=Storage Elastic Modulus [Pa]×Centrifugal Retention [g/g] - - - (I).SELECTED DRAWING: None【課題】吸水性能に優れ、吸収体に使用した場合に荷重下での吸収性能を向上させることができる吸水性樹脂及びその吸水性樹脂を含む吸収体を用いた吸収性物品を提供する。【解決手段】本発明に係る吸水性樹脂は、水溶性エチレン性不飽和単量体を内部架橋剤の存在下で重合させ、かつ後架橋剤で後架橋することにより得られる吸水性樹脂であって、４．１４ｋＰａ荷重下での生理食塩水吸水能が１６ｍＬ／ｇ以上であり、かつ当該吸水性樹脂全体の割合に占める１５０～８５０μｍの粒子の質量割合が８５質量％以上であり、さらに３００～４００μｍの粒子の質量割合が２０質量％以上であり、下記式（Ｉ）で表される吸収容量弾性指数が６８０００以上である吸水性樹脂である。吸収容量弾性指数＝貯蔵弾性率［Ｐａ］×遠心保持率［ｇ／ｇ］ ・・・（Ｉ）【選択図】なし
