[Problems] To provide a process for preparing a water-absorbent resin which can be suitably used in a hygienic material, the water-absorbent resin having a large amount of water-retention, a large amount of water absorption under pressure, a high water absorption rate, and a small amount of water-soluble substance. [Solving Means] A process for preparing a water-absorbent resin comprising carrying out a reversed phase suspension polymerization in multi-steps of two or more steps when the water-absorbent resin is prepared by subjecting a water-soluble ethylenically unsaturated monomer to the reversed phase suspension polymerization, said process for preparing a water-absorbent resin being characterized by adding an aminocarboxylic acid compound to at least one step in the second and subsequent steps, to carry out the polymerization reaction.本發明係提供一種吸水性樹脂之製造方法,其中該吸水性樹脂之保水量及加壓下之吸水量較高、吸水速度較快且水可溶性成分較少,因而可適用於衛生材料。本發明係提供一種吸水性樹脂之製造方法,其特徵在於:於將水溶性乙烯性不飽和單體進行逆相懸浮聚合而製造吸水性樹脂之時,以2階段以上之多階段進行逆相懸浮聚合,於第二階段以後之至少一個階段中,添加胺基羧酸系化合物進行聚合反應。1...滴定管部2...導管3...測定台4...測定部5...吸水性樹脂10...滴定管11...空氣導入管12,13...旋塞14...橡皮栓40...圓筒41...尼龍網眼42...鉛墜X...測定裝置
