A light diffusing film which is excellent in luminance uniformity and which exhibits no partial deterioration in light transmittance, thereby eliminating the formation of black spots. The light diffusing film, which has a monodisperse light diffuser and a light diffusing layer consisting of a light diffuser and a binder resin on one plane of a base, in which the lamination ratio is 10% or less and the diameter of flocculated particles in the light diffuser is 50 .mu.m or less, exhibits excellent luminance and thermal properties, so that it can be suitably used in various kinds of picture display devices, in particular, in a display device employing LED (light emitting diode) lamps or an LCD (liquid crystal display device) backlight system.