To obtain a highly water-absorbing resin which has a large average particle diameter and a highly resin-fixing property and is useful for paper diapers, and the like, by feeding the aqueous solution of a specific water-soluble polymerizable monomer to subject the monomer to a suspension polymerization.

This method for producing a highly water-absorbing resin comprises feeding a water-soluble polymerizable monomer aqueous solution containing a phosphate ester-based dispersant of the formula {R1 is an 8 to 30C (substituted) alkyl, a (substituted) aryl; R2 is OH, R1O-(CH2CH2O)n [(n) is 1 to 30]) to a hydrophobic organic solvent containing the phosphate ester- based dispersant of the formula to subject the water-soluble polymerizable monomer to a suspension polymerization. The dispersant contained in the solvent is preferably the same as the dispersant contained in the monomer, and the concentration (Y) of the dispersant in the monomer aqueous solution and the concentration (X) of the dispersant in the solvent are preferably independently 0.05 to 2 wt.%, respectively.