Provided is an optical fiber ribbon capable of achieving higher density and reduction in diameter and accurately placing optical fibers in V-shape grooves in a fusion machine without failure. The optical fiber ribbon 1 includes three or more of optical fibers 2 arranged in parallel and connecting portions 3 each connecting adjacent two optical fibers 2 together, the connecting portions 3 being intermittently provided in each of a ribbon longitudinal direction and a ribbon width direction. The optical fiber ribbon 1 has an outer diameter dimension of the optical fibers 2 which is set to smaller than or equal to 220 mu m, and has a distance between the centers of the adjacent two optical fibers which is set to 250+-30 mu m.