To provide a plastic clad optical fiber clad with a resin having excellent transmission loss and having high mechanical characteristics and more particularly Young's modulus.

The clad of this plastic clad optical fiber is formed of a copolymer which contains a monofunctional monomer expressed by the formula CH2= CR1COO(CR23)2R3 [where, R1 and R2 are deuterium or fluorine, R3 is deuterium or halogen atom] as a polymn. component and in which another polymn. component is urethane di(meth)acrylate oligomer. This copolymer is a polymer of ≤60% in the carbon-hydrogen bond content over the entire part of the polymer.