PURPOSE: To obtain highly water-absorbing resin particles which suffer little from the deposition of polymer scales during their production and have a suitable mean particle diameter and a sharp particle diameter distribution by subjecting a partially neutralized salt of (meth)acrylic acid to a reversed-phase suspension polymerization reaction and drying the obtained resin particles in a specified manner.

CONSTITUTION: An aqueous solution of (meth)acrylic acid or a water-soluble unsaturated monomer based on a water-soluble salt of (meth)acrylic acid is subjected to a reversed-phase suspension polymerization reaction in the presence of a β-1,3-glucan and a free-radical polymerization initiator in the presence of absence of a crosslinking agent in a hydrocarbon solvent to obtain highly water-absorbing resin particles. A polyfunctional compound having at least two COOH-reactive functional groups in the molecule is adhered to the surfaces of these particles, and the treated particles are treated with a water-soluble carboxylic polymer to obtain the objective highly water-absorbing resin. According to this process, the obtained resin has high strengths of a swollen gel, resistance to the formation of agglomerates of insufficiently wetted particles, an improved water-absorbing capacity, and an improved water absorption rate.