To provide a plastic optical fiber using amorphous fluorinated polymers whereby transmission loss and bending loss are low, no cracking takes place during stretching, and a wide range of molding conditions is acceptable.A plastic optical fiber comprising an inner layer, an outer layer having a refractive index lower than the refractive index of the inner layer, and a protective coating layer covering the outer periphery of the outer layer, wherein the inner layer contains an amorphous fluorinated polymer (a) having no C—H bond, the outer layer contains an amorphous fluorinated polymer (c) which may have a C—H bond only at a terminal of the main chain, the glass transition temperature (Tgc) of the fluorinated polymer (c) is at least the glass transition temperature (Tga) of the fluorinated polymer (a), the plastic optical fiber is a stretched one, the fracture elongation of the fluorinated polymer (a) and the fracture elongation of the fluorinated polymer (c) are at least 120% and larger than the stretching ratio.