An optical element for use in an optical pickup apparatus includes a
substrate made of resin; an antireflection layer coating the substrate
and having a low refractive index layer and a high refractive index
layer, wherein the resin includes a polymer with an alicyclic
structure, the low refractive index layer is formed of a material
selected from the group consisting of silicon oxide; aluminum fluoride;
yttrium fluoride; magnesium fluoride; a mixture of silicon oxide and
aluminum oxide; and a mixture thereof, the high refractive index layer is
formed of a material selected from the group consisting of scandium
oxide; niobium oxide; lanthanum oxide; praseodymium titanate; lanthanum
titanate; lanthanum aluminate; yttrium oxide; hafnium oxide; zirconium
oxide; tantalum oxide; a mixture of tantalum oxide and titanium; silicon
nitride; and a mixture thereof.