PURPOSE: To simply and quickly obtain a desired coating silica dispersion in a short time with certainty.

CONSTITUTION: A process for preparing a coating silica dispersion by removing an alkali from an aq. soln. of an alkali silicate, adding a growth inhibitor to the resulting silica dispersion, removing therefrom water and dispersing the remainder with a diluent, wherein the alkali is removed by adding an acid to the aq. soln. of an alkali silicate to form a salt through the neutralization of the acid with the alkali, distilling off water in the aq. soln., dispersing the remainder with the diluent, and removing the resulting precipitate by filtration.