Disclosed is a chemical mechanical polishing aqueous dispersion comprising (A1) first fumed silica having a specific surface area of not less than 10 m2/g and less than 160 m2/g and an average secondary particle diameter of not less than 170 nm and not more than 250 nm and (A2) second fumed silica having a specific surface area of not less than 160 m2/g and an average secondary particle diameter of not less than 50 nm and less than 170 nm. Also disclosed is a chemical mechanical polishing method using the chemical mechanical polishing aqueous dispersion. According to the chemical mechanical polishing aqueous dispersion and the chemical mechanical polishing method, a chemical mechanical polishing process wherein a barrier metal layer and a cap layer can be efficiently removed by polishing and damage to an insulating film material of a low dielectric constant present in the underlying layer is reduced can be carried out.