A polarization separating film and a backlight unit including the same are provided. The polarization separating film includes a first layer including an entry surface through which light is incident, and formed of optically isotropic materials, a second layer formed on the first layer and formed of optically anisotropic materials, and a fine pattern formed between the first layer and the second layer, wherein first polarized light of the light is transmitted and second polarized light of the light perpendicular to the first polarized light is reflected.