PURPOSE: To obtain the title resin excellent in water absorptivity and useful as a water-absorptive or water-retentive material of high quality, by polymerizing a specified alkali metal acrylte with an aqueous pulp dispersion in the presence of a radical initiator and crosslinking the product.

CONSTITUTION: An aqueous dispersion is obtained by slurrying a mixture of a monomer (A) comprising at least 70wt.% metal acrylate (a) in which 60W90mol.% of the carboxyl groups are neutralized with an alkali metal and, optionally, a hydrophilic (polyfunctional) monomer (b) (e.g.m acrylamide) with a 4W20wt.%, based on component A, pulp (B) in water (C) in an amount to give an A to C weight ratio of 40W80/60W20. This dispersion is polymerized at 0.1W1atm for 10W20min in the presence of 0.05W0.5wt.%, based on component A, radical initiator [e.g., 2,2'-azobis(2-amidinopropane)], and the produce is crosslinked.