If such copolymers as mentioned above are employed as the cladding material of an optical fiber of this invention, for instance, such disadvantage as a low heat distortion temperature of a cladding material in which 1H, 1H, 5H-octafluoropentyl methacrylate polymer is used as the cladding component, or as a fragile cladding material in which 1H, 1H-trifluoroethyl methacrylate polymer is employed as