To provide a dispersion containing a dispersant, capable of producing a water-soluble polymer in good efficiency while suppressing thickening at the time of polymerization when a dispersion polymerization is carried out in an aqueous solution of a salt in the coexistence of a high-molecular dispersant, and further to provide a method for efficiently producing the dispersion.

This polymer dispersion contains both of fine particles of the water-soluble polymer having ≤100 μm particle diameters and one or more kinds of ionicities selected from cationic, nonionic and ampholytic, and at least one kind or more of a graft copolymer having a specific side chain as the dispersant, coexisting in the aqueous solution of the salt. The polymer dispersion is efficiently produced by making at least one kind or more of the graft copolymer coexist at the time of polymerization.