A light diffusion film (20) having small back scattering can be obtained by using fibers having two kinds of birefringent regions (21A) and (21B). An outer portion of fiber (21) is a first birefringent region 21A and an inner portion of fiber (21) is a second birefringent region (21B). While the first birefringent region (21A) is in contact with a transparent resin (22), the second birefringent region (21B) is not in contact with the transparent resin (22). When a refractive index (n1) in major axis direction of the first birefringent region (21A) is a value between a refractive index n2 in major axis direction of the second birefringent region (21B) and a refractive index n0 of the transparent resin (22), interface reflection between the transparent resin (22) and the fiber (21) can be reduced, which leads to obtain a light diffusion film (20) having small back scattering.