Zirconium oxide nanoparticles

The purpose of the present invention is to easily obtain, without using or using a smaller amount of a sulfate aqueous solution such as a MgSO 4 aqueous solution, zirconium oxide particles which include metallic elements such as rare earth oxides (preferably stabilized with a metallic element) and which exhibit good dispersibility with respect to an organic medium. These zirconium oxide nanoparticles are coated with a first carboxylic acid which has three or more carbon atoms and which is at least one type of a primary carboxylic acid and a secondary carboxylic acid. The zirconium oxide nanoparticles include at least one type of metallic element M selected from the group consisting of rare earth elements, Al, Fe, Co, Sn, Zn, In, Bi, Mn, Ni, and Cu.