Provided are a silica-coated mixed crystal oxide particle which has high dispersibility, excellent visible light transparency and superior ultraviolet-shielding capability and which is sufficiently reduced in the photocatalytic activity; an economical production process thereof; and an ultraviolet-shielding cosmetic material containing the silica-coated mixed crystal oxide particle, which is particularly excellent in the visible light transparency. The surface of a mixed crystal oxide particle having a BET specific surface area of 10 to 200 m.sup.2/g and containing primary particles in a mixed crystal is covered with a dense and thin film silica.