To provide a method for producing a water-soluble polymer which includes a wet crushing step of crushing secondary particles of a water-soluble polymer in water-soluble polymer slurry, wherein the method is improved so that good operation of a wet crusher can be carried out.

The method for producing a water-soluble polymer sequentially includes: a polymerization step of obtaining slurry of (co)polymer particles by suspension polymerization of an aqueous monomer solution containing an N-vinylcarboxylic acid amide or of this and another copolymerization component and a polymerization initiator in a hydrophobic organic solvent in the presence of an emulsifier; a modification step of modifying the resulting slurry of (co)polymer particles by adding an acid thereto; a distillation/dehydration step of the resulting water-soluble polymer slurry; a separation step of the hydrophobic organic solvent; and a drying step of the recovered water-soluble polymer, wherein, between the distillation/dehydration step and the separation step of the hydrophobic organic solvent, a wet crushing step of crushing secondary particles of the water-soluble polymer in the water-soluble polymer slurry is provided while keeping the temperature of the water-soluble polymer slurry in the range of 40-55°C.