Light diffusing methacrylic resin light guide body and a surface light source device having the same

The present invention reduces the occurrence of the dark line, and aims to provide a methyl methacrylate-based resin light guide capable of improving screen quality of the surface light source device, the light guide body, methyl methacrylate-based resin to 100 parts by mass, the difference absolute value of the refractive index of the methyl methacrylate resin is 0.001 to 0.02 in and and less fine 10μm average particle diameter of 1μm or 0.01 parts by mass or more 0. that 5 are dispersed at a ratio of less parts by mass, wherein, is used for a surface light source device.