The anti-reflection optical element of the present invention achieves reduction of surface reflection by providing a multi-layered anti-reflection film directly or indirectly on an optical component made of a plastic. The anti-reflection optical element of the present invention uses a multi-layered anti-reflection film comprising at least one high refractive index film layer which is a film of mixed metal oxides comprising tantalum oxide, zirconium oxide and yttrium oxide deposited by evaporation process, and thereby has solved the problems of conventional anti-reflection optical elements that their optical, mechanical and chemical properties are deteriorated with the lapse of time.