To provide a biaxially oriented polyester film in which a prism layer composed of a number of prism units is formed on one surface of a film, with excellent adhesion between the prism layer and a polyester film and which has a superior light scattering property.

The light scattering biaxially oriented polyester film for a prism sheet includes a highly adhesive layer on at least one surface of a laminated polyester film having a light scattering layer containing 0.05-10 wt.% of inactive particles with an average particle size of 0.5-50 m, wherein a haze of the polyester film falls into the range of 10-80%.