The present invention is related to a process of manufacturing rutile high-purity titania nano sols in a pure aqueous medium having no ionic impurities. In more detail, the present invention is related to a process for manufacturing titania nano sols, in which high-purity rutile titania nano particles are dispersed stably, through the hydrolysis of titanium tetraisopropoxide in an aqueous solution containing hydrogen peroxide (H.sub.2O.sub.2), and simultaneously with the hydrolysis, formation of peroxotitanate precursors, and hydrothermal treatment of them at 50-120.degree. C.