Object An object of the present invention is to provide a process for producing a water-absorbent resin by employing a reversed suspension polymerization method, by which a water-absorbent resin having a small particle size and a narrow particle size distribution can be produced. Means for Achieving the Object A process for producing a water-absorbent resin comprising subjecting a water-soluble ethylenically unsaturated monomer to a reversed phase suspension polymerization in a petroleum hydrocarbon dispersion medium containing a surfactant and a polymeric dispersion agent, wherein the polymeric dispersion agent is a Polymeric protective colloid having a weight average molecular weight (Mw) of 2,000 to 15,000 and a molecular weight distribution (Mw/number average molecular weight (Mn)) of 3 to 50.本發明之目的係在於提供藉由反相懸浮聚合法來製造吸水性樹脂的方法,該製造方法可提供粒徑小且粒度分布狹窄之吸水性樹脂。一種吸水性樹脂的製造方法,係使水溶性乙烯性不飽和單體,在含有界面活性劑及高分子系分散劑之石油系碳氫化合物分散介質中,反相懸浮聚合來製造吸水性樹脂者,其特徵在於該高分子系分散劑係重量平均分子量(Mw)為2000~15000,且分子量分布(Mw/數量平均分子量(Mn))為3~50之高分子保護膠體。
