OPTICAL FIBER RIBBON

An optical fiber ribbon (1A) is provided with a plurality of coated optical fibers (11) arranged in parallel in a direction orthogonal to the longitudinal direction thereof, and a collective covering layer (20) that covers the respective outer peripheries of the plurality of coated optical fibers (11). The collective covering layer (20) includes a coupling part (21) that couples adjacent coated optical fibers (11) in at least some of the plurality of coated optical fibers (11). The outer diameters of the plurality of coated optical fibers (11) are each 215 µm or less. In the cross-sectional view of the coated optical fibers (11), the collective covering layer (20) is provided with a thick portion (22), and at least two thin portions (23) in which the thickness of the collective covering layer (20) is smaller than the thickness of the collective covering layer (20) in the thick portion (22). The difference between the thickness of the collective covering layer (20) in the thick portion (22) and the thickness of the collective covering layer (20) in the thin portion (23) is 5-19 µm.