There is provided a sol of modified metal oxide composite colloidal particles including titanium oxide having a high refractive index and excellent light resistance and weather resistance that discoloration of the colloidal particles by photoexcitation is almost completely inhibited. A modified metal oxide composite colloidal particle comprises; a titanium oxide-tin oxide-zirconium oxide-tungsten oxide composite colloidal particle (A) having a primary particle diameter of 2 to 50 nm and having a SnO2/TiO2 molar ratio of 0.1 to 1.0, a ZrO2/TiO2 molar ratio of 0.1 to 0.4, and a WO3/TiO2 molar ratio of 0.03 to 0.15, as a core; and a tungsten oxide-tin oxide-silicon dioxide composite colloidal particle (B) having a primary particle diameter of 1 to 7 nm with which a surface of the core is coated.