To provide an ionic water-soluble polymer which is low in transport cost and environmental load and a method for producing the same, and to provide a cationic water-soluble polymer which exhibits excellent functions in application to a flocculant, in particular, in application to dehydration of sludge and dehydration of paper sludge and in a method for making paper from papermaking stock after adding the polymer to the stock.

The ionic water-soluble polymer is obtained by preparing a dispersion comprising a continuous phase containing a dispersant and a hydrophobic dispersion medium and a dispersed phase essentially containing a cationic monomer and a polyfunctional monomer having a plurality of unsaturated double bonds, subjecting the dispersion to reversed phase suspension polymerization, and drying the resultant polymer. The ionic water-soluble polymer includes a powder which develops a specific ionic character.