Slurry rheology modifier

A slurry rheology modifier comprises a first water-soluble low-molecular compound [referred to hereinafter as compound (A)] and a second water-soluble low-molecular compound [referred to hereinafter as compound (B)] being different from the compound (A), wherein the viscosity of an aqueous solution at 20° C. prepared by mixing an aqueous solution SA (with a viscosity at 20° C. of 100 mPa·s or less) of compound (A) with an aqueous solution SB (with a viscosity at 20° C. of 100 mPa·s or less) of compound (B) in the ratio of 50/50 by weight can be at least twice as high as the viscosity of either aqueous solution before mixed.