A process for producing a polishing composition, which comprises preliminarily adjusting water to pH 2-4, adding from 40 to 60 wt % of fumed silica to the water under high shearing force, adding water to lower the viscosity to 2-10000 cps, stirring the mixture under low shearing force for at least 5 minutes, adding water to lower the fumed silica concentration to 10-38 wt %, and adding a basic substance under vigorous stirring to raise the pH to 9-12.