A light diffusion film which has excellent light transmittance and light diffusibility while maintaining excellent heat resistance, mechanical strength and thickness accuracy intrinsic to a biaxially stretched film, and is suppressed in generation of curling after heat treatment, wherein the film comprises a biaxially stretched laminated film having a supporting layer consisting of a crystalline polyester, and a light diffusion layer laminated on at least one side of the supporting layer by a co-extrusion method, wherein the light diffusion layer comprises 60 to 98 parts by mass of the crystalline polyester and 2 to 40 parts by mass of a light diffusion additive incompatible with the polyester, and the light diffusion film has a planar orientation degree (ΔP) of 0.080 to 0.160, a total light transmittance of 85% or more, and a haze of 30% or more.