Optical fiber ribbon

An optical fiber ribbon comprising:

• a plurality of optical fibers arranged in parallel in a direction orthogonal to a longitudinal direction of the plurality of optical fibers;
• and
• a collective coating layer covering an outer periphery of each of the plurality of optical fibers, wherein
• the collective coating layer includes a connected portion at which the optical fibers adjacent to each other are connected in at least a part of the plurality of optical fibers,
• an outer diameter of each of the plurality of optical fibers is 215 μm or less,
• in a cross-sectional view of each of the optical fibers, the collective coating layer includes a thick portion and at least two thin portions in each of which a thickness of the collective coating layer is smaller than a thickness of the collective coating layer in the thick portion, and
• a difference between the thickness of the collective coating layer in the thick portion and the thickness of the collective coating layer in the thin portion is 5 μm or more and 19 μm or less.