COATED OPTICAL FIBER

PROBLEM TO BE SOLVED: To obtain a coated optical fiber which is formed by using a halogen element-free fire-retardant phosphorus-containing polyethylene(PE) outer resin coating layer, is high in hygroscopicity by this phosphorus-containing PE outer resin coating layer, is capable of efficiently obstructing the adverse influence to be exerted on the optical characteristics of the optical fiber UV by granular phosphorus and is accepted in a VW-1 test vertical tray fire-retardance test of UL. SOLUTION: The coated optical fiber comprises the optical fiber UV, a halogen element-free fire-retardant inner resin coating layer to coat the outer peripheral part of the optical fiber UV so as not to impart moisture to the optical fiber UV and not to adversely affect its optical characteristics and the halogen element-free fire-retardant phosphorus-containing PE outer resin coating layer coating the outer peripheral part of this fire-retardant inner resin coating layer.