A water-absorbing agent according to the present invention includes water-absorbent resin particles having an internal cross-linked structure, wherein a vicinity of a surface of the water-absorbent resin particle is cross-linked with a surface cross-linking agent, and the water-absorbent resin particle has therein a sea-island structure having (i) part containing a first water-soluble multivalent metal salt such as aluminum sulfate and (ii) part not containing the first water-soluble multivalent metal salt. With this arrangement, it is possible to provide a water-absorbing agent having less water-soluble component content, more excellent liquid permeability, and more excellent water retention under pressure than the conventional water-absorbing agent.本發明之吸水劑包含具有內部交聯構造之吸水性樹脂粒子,在該吸水性樹脂粒子之表面附近藉由交聯劑交聯,該吸水性樹脂粒子之內部則成為海島構造,該海島構造具有含硫酸銨等第一水溶性多價金屬鹽之部分及不含該第一水溶性多價金屬鹽之部分。藉此,與先前之吸水性樹脂相比,可提供水溶性成分量較少、通液性優異且加壓時保水能力優異之吸水劑。
