To obtain a thermoplastic resin composition which is excellent in light transmission properties and light diffusibility and gives a molded item having a good external appearance by compounding a transparent thermoplastic resin with silicone particles prepared by coating specific spherical silicone rubber particles with a polyorganosilsesquioxane resin.

This composition is prepared by compounding a transparent thermoplastic resin, preferably a methacrylic or MS resin, with silicone particles prepared by coating spherical silicone rubber particles having an average particle size of 0.1-50 μm with a polyorganosilsesquioxane resin preferably in an amount of 0.5-500 wt.% of the rubber particles. Preferably, the amount of the silicone particles in the composition is 0.0003-30 wt.%. The composition is injection molded to give a light-diffusible molding or a light-diffusible sheet, those products being useful for lighting applications.