In a C band and an L band, the effective refractive indices of light propagating through the cores 11 and 21 adjacent to each other are different from each other such that a magnitude of crosstalk of light of a highest-order LP mode commonly propagating through the cores 11 and 21 adjacent to each other between the cores 11 and 21 adjacent to each other becomes a peak at a bending diameter smaller than a diameter of 100 mm, and the core has a higher refractive index in a center portion than in an outer circumferential portion such that a differential mode group delay of the cores 11 and 12 is 700 picoseconds/km or less.