Provided is a method for producing a water absorbent resin, which promotes the formation of interconnected voids (continuous gas bubbles) in a foamed polymer (foam-like water absorbent resin) by a more convenient method, and produces with high efficiency a water absorbent resin which exhibits a high water absorption rate even when stepped into a sheet form or a powder form in hygiene articles and the like. Disclosed is a method for producing a polyacrylic acid-type water absorbent resin, comprising (A) a step of obtaining an aqueous solution of acrylic acid-type monomers containing gas bubbles dispersed therein； (B) a step of polymerizing the aqueous monomer solution and thereby obtaining a foamed polymer； and (C) a step of heating and drying the foamed polymer,wherein gas bubbles are incorporated such that the volumetric expansion factor defined by the following formula (1)；[Formula 1]Volumetric expansion factor=(Volume of aqueous monomer solution after gas bubble dispersion)/(volume of aqueous monomer solution before gas bubble dispersion) Formula (1)；exceeds 1.1 times, and the aqueous monomer solution having a monomer concentration defined by the following formula (2)； [Formula 2]Monomer concentration [wt %]=(Weight of a monomer)/{(weight of a monomer)+(weight of solvent)}×100 Formula (2)；of 40% by weight or greater is boiling polymerized at a temperature of 100° C. or higher.
