To provide a method for the efficient production of a rutile-type titanium oxide sol having excellent dispersibility wherein grain size as measured by dynamic light scattering is 5 to 100 nm. A method for producing a rutile-type titanium oxide sol having a grain size as measured by dynamic light scattering of 5 to 100 nm comprises the following steps (a) and (b): Step (a): a step for preparing a titanium-containing aqueous solution having a concentration of 0.1 to 15 mass% in terms of TiO2 whereby an aqueous solution is prepared by mixing an aqueous tin oxalate solution, a titanium alkoxide, oxalic acid, a quaternary ammonium hydroxide, and water such that, per mole of titanium atoms, the ratio of tin atoms is 0.1 to 0.8 mol, the ratio of oxalic acid is 0.01 to 5 mol, and the ratio of quaternary ammonium hydroxide is 0.1 to 3.5 mol; and Step (b): a step for hydrothermal treatment, at 100 to 200 degree centigrade, of the titanium-containing aqueous solution obtained by step (A).