Provided are: a water-absorbent resin that has excellent water absorption performance and in which discoloration is minimized before and after long-term storage under high temperatures and high humidity and an absorbent article that uses the water-absorbent resin. The water-absorbent resin is obtained by polymerizing a water-soluble ethylenically unsaturated monomer under the presence of an internal crosslinking agent and using a post-crosslinking agent to post-crosslink the result. The water-absorbent resin satisfies the following properties: (A) the saline water absorption capacity is 55 g/g or more, the saline water absorption capacity under a load of 4.14 kPa is 15 ml/g or more, and the residual monomer content is 300 ppm or less and (B) yellowness is 5.0 or less and the rate of change ([Delta]YI) in yellowness after being left for ten days under an environment of 70 DEG C and 90% relative humidity is 10 or less.本發明提供一種吸水性樹脂及使用該吸水性樹脂而成的吸收性物品,該吸水性樹脂具有優異的吸水性能,並且,即使在高溫高濕下長期保管的前後,仍能夠抑制著色。本發明的吸水性樹脂,其是藉由在內部交聯劑的存在下使水溶性乙烯性不飽和單體進行聚合,並且利用後交聯劑進行後交聯來獲得,其中,該吸水性樹脂滿足以下的性質:(A)生理食鹽水吸水能力是55g/g以上,在4.14kPa荷重下的生理食鹽水吸水能力是15ml/g以上,並且殘留單體含量是300ppm以下;(B)黃色度是5.0以下,並且在70℃、90%相對濕度的環境下放置10天後的黃色度的變化率(△YI)是10以下。
