To provide a light diffusing film which can improve the display grade of a surface light source device and liquid crystal display device by using anisotropic light diffusion.

A diffusing film 7 has a diffusion layer consisting of: a continuous phase of resin (a cyclic polyolefin system resin, etc.) of a low intrinsic double refraction index; and a dispersion phase of resin (non-crystalline polyester, styrene system resin, etc.) of a refractive index different from the refractive index of the continuous phase. The mean aspect ratio of the dispersion phase is greater than 41 in order to impart anisotropy to transmitted light. The diffusion film 47 is applicable to a display device 41 consisting of a liquid crystal display unit 42 and a surface light source unit 43. The unit 43 is provided with a tubular light source 44, a light guide member 45, the optical diffusion film 47, and a prism sheet 48. The film 47 diffuses the light from the light source (fluorescent lamp) of the surface light source device (back light) to uniformly illuminate the unit 42.

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