a metal oxide doped cerium oxide has an excellent ultraviolet ray shielding effect and transparency and reduced catalytic activity . the doping mextal oxide is an oxide of a metal ion having larger ion radius than that of ce 4 + and / or lower valence metal ion than ce 4 + , such as ca 2 + , y 3 + , la 3 + , nd 3 + , eu 3 + , tb 3 + , sm 3 + , mg 2 + , sr 2 + , ba 2 + , ce 3 + . the metal oxide doped cerium is prepared by reacting aqueous solution of cerium salt , aqueous solution of metal ion having larger ion radius than that of ce 4 + and / or lower valence metal ion than ce 4 + and alkali at a temperature lower than 60 ° c . and at ph higher than 5 . an oxidizing agent may be present together with the alkali or added subsequently . resin compositions or cosmetic compositions blended with the metal oxide doped cerium oxide have improved ultraviolet shielding effect without spoiling transparency in the visible ray region .