The invention provides a novel method for producing a water-absorbent resin comprising: subjecting at least one water-soluble ethylenic unsaturated monomer to reversed-phase suspension polymerization in a petroleum hydrocarbon dispersion medium, the reversed-phase suspension polymerization being conducted using a 0.00005 to 0.00016 mol of water-soluble azo initiator for radical polymerization per mol of the water-soluble ethylenic unsaturated monomer in the presence of 0.000015 to 0.00015 mol of hypophosphorous compound per mol of the water-soluble ethylenic unsaturated monomer. According to the method, the environmental impact can be lessened by reducing the amount of petroleum hydrocarbon dispersion medium released to the outside of the system, and the method makes it possible to obtain a water-absorbent resin having a high water-retention capacity and water-absorption capacity under a load, and a small content of water soluble component at the same time.
