To provide a light diffusing sheet which has a high transmission factor and high diffusion coefficient and yet is light in weight and high in strength so as to correspond to a large area application.

In a light diffusing sheet 1 having a layer of vinyl chloride resin 2 which is to be arranged between a light source and a body under irradiation, the layer of vinyl chloride resin 2 is reinforced with a polyester monofilament fiber sheet 3. Preferably, the layer of vinyl chloride resin 2 contains a light diffusing agent. The polyester monofilament fiber sheet 3 is, for example, a wooven fabric. Further, a layer of fluorocarbon resin 5 can be arranged on the light diffusing sheet thus fabricated.