To provide a side light extraction type light fiber capable of extracting light having high brightness at a viewing angle. Means for solving: a light fiber comprising: a core (1) in the center portion, and a cladding arranged around the core, characterized in that the cladding comprises: (i) a light diffusive layer (3) comprising a light diffusive portion made of a light diffusive material containing, as a binder, a polymer having a refractive index smaller than that of the core, which is provided in closely contact with the core in a wall thickness of 1 to 300 .mu.m in a circumferential direction, and (ii) a protective layer (4) made of a light transmitting resin material, which is formed to integrate with the light diffusive layer and covers the light diffusive layer.