An inorganic oxide particles which have a minute particle diameter at which no interference fringes occur in a coating film and high transparency can be secured even when applied to a high refractive index substrate, and in which excitation by ultraviolet radiation is almost completely suppressed, a coating composition containing such particles, and an optical member having a cured film formed from the coating composition. Inorganic oxide particles obtained by bonding an organosilicon compound having a nitrogen-containing heterocyclic group to the surface of modified metal oxide colloid particles (C) having an average particle diameter of 2 to 100 nm, which include metal oxide colloid particles (A) having an average primary particle diameter of 2 to 60 nm as nuclei and with the nuclei surface coated with a coating composed of inorganic oxide colloid particles (B) having an average primary particle diameter of 1 to 4 nm.