[Objective] To detect abnormalities in optical fibers by using a phenomenon specific to optical fiber tapes including plural optical fibers arranged parallel to each other and connected together intermittently. [Solution] This optical fiber tape manufacturing method involves: a step of forming connecting parts that connect together adjacent optical fibers among a plurality of optical fibers arranged parallel to each other while applying tension to the optical fibers, and thus forming an optical fiber tape in which the connecting parts are intermittently disposed; a step of reducing the tension applied to the optical fiber tape; and a step of measuring a thickness of the optical fiber tape with reduced tension from a direction parallel to a tape plane on a path of the optical fiber tape.