There is provided a sol in which surface-modified colloidal particles are dispersed in a liquid, wherein the surface-modified colloidal particles are obtained by using anhydrous zinc antimonate colloidal particles, metal oxides comprising tin atom, zinc atom, antimony atom and oxygen atom, or tin oxide-doped anhydrous zinc antimonate colloidal particles as nuclei, and by coating the surface of the nuclei with an aluminum-containing substance (e.g., an aluminum chelating agent), a polymer type surfactant (e.g., a polycarboxylic acid ester or polyethylene glycol monoaliphatic acid ester surfactant) or both of them. The anhydrous zinc antimonate sol is used for several purposes such as transparent antistatic materials in the form of resin, plastic, glass, paper, magnetic tape or the like, transparent UV absorbers, transparent heat radiation absorbers, high refractive index hard coating agent, anti-reflective agent and the like.