Abstract: A process for producing a highly water absorptive polymer comprising the steps of subjecting a water-soluble ethylenically unsaturated monomer comprising as the main component acrylic acid and/or an alkali metal or ammonium salt thereof, and optionally containing a crosslinking agent to a water-in-oil type of reverse-phase polymerization in the presence of water, a water-soluble radical polymerization initiator, a dispersant and a hydrophobic hydrocarbon solvent to form a slurry of water-containing particles of a highly water absorptive polymer in the solvent, adding a polymerizable monomer to the slurry, and polymerizing the polymerizable monomer to obtain agglomerates of the particles of the highly water absorptive polymer.