To effectively prevent slurry containing mineral particles from becoming flocculated by using a dispersant containing a specific water-soluble polymer, in a dispersion of granular solids in a medium containing water or at least one dispersant.

When a dispersion or slurry of mineral solids which tend to flocculate or precipitate or to be phased out, for example, slurry of calcium carbonate for paper manufacturing industry, is produced, a medium containing water and at least one dispersant is used. In this case, a dispersant containing a water-soluble polymer represented by formula I is used. In formula I, X is H, Na, K, Ca, Mg, NH4+ or A. A is a polymer, a copolymer or a water-soluble salt thereof in a polymerized state and including those represented by formula II (wherein, R1 is H, OH, an alkyl and the like; R2 is H, and alkyl, an alkoxy and the like and R3 is H, Na, K, an alkyl and the like).