There is provided provide a method for efficiently producing a rutile type titanium sol having a particle diameter based on dynamic light scattering method of 5 nm to 100 nm that is excellent in dispersibility. The method for producing a rutile type titanium oxide sol comprising: process (a): mixing metastannic acid, a titanium alkoxide, a quaternary ammonium hydroxide, oxalic acid, and water so as to contain 0.02 moles to 0.8 moles of tin atoms, 0.1 moles to 3.5 moles of the quaternary ammonium hydroxide, and 0.1 moles to 8.0 moles of the oxalic acid with respect to 1 mole of titanium atoms of the titanium alkoxide to prepare a titanium-containing aqueous solution with a concentration in terms of TiO2 of 0.1% by mass to 15% by mass and process (b): subjecting the titanium-containing aqueous solution obtained in process (a) to a hydrothermal treatment at a temperature from 100° C. to 170° C.
