A method for evaluating the quality of abrasive grains for polishing glass, which comprises adding abrasive grains to be measured, to an aqueous medium having silica dissolved therein, to have the silica adsorbed on the abrasive grains under such a condition that the silica undergoes substantially no polymerization in the aqueous medium, followed by solid-liquid separation to separate the abrasive grains from the mother liquor, and measuring the concentration of silica remaining in the mother liquor to measure the adsorption rate () of silica on the abrasive grains.