The aqueous dispersion comprising (A) abrasive grains, (B) at least one compound selected from the group consisting of 2-bromo-2-nitro-1,3-propanediol, 2-bromo-2-nitro-1,3-butanediol, 2,2-dibromo-2-nitroethanol, and 2,2-dibromo-3-nitrilopropionamide, and (C) an organic component other than the compounds of component (B is disclosed. The aqueous dispersion has no problem of rotting even if stored or used in a neutral pH region and produces an excellent polished surface with almost no dishing or scratches, when applied particularly to the STI process for manufacturing of semiconductor devices.