Provided are silica-based fine particle dispersion sols, processes for producing the sols, coating compositions containing the dispersion sol, curable coating films obtained from the coating composition, and substrates having the coating film. The process including (1) mixing an aqueous aluminate solution to an alkaline silica sol which contains water-dispersible silica fine particles in a given ratio; (2) heating the mixture liquid obtained in step (1) to 60 to 200° C. and stirring the mixture liquid at the temperature for 0.5 to 20 hours; and (3) contacting the mixture liquid obtained in step (2) with a cation exchange resin to remove by ion exchange alkali metal ions contained in the mixture liquid and thereby controlling the pH of the mixture liquid to be in the range of 3.0 to 6.0.