PURPOSE: To prevent the increase in the vibration of an optical fiber between the draw-starting time and the target line speed-reaching time and simultaneously enable to coat the optical fiber with a resin by controlling the flow of a cooling gas, when the drawn optical fiber is cooled in a cooling zone.

CONSTITUTION: The tip of an optical fiber matrix is thermally softened and drawn, and the formed optical fiber is passed through a cooling zone and simultaneously cooled with the flow of a cooling gas. The cooled optical fiber is passed through a resin coating device to coat the outer periphery of the optical fiber with a resin. In the process, the flow of the cooling gas is adjusted to control the maximum vibration amplitude to ≤0.2mm and also control the temperature of the optical fiber entering a resin coating device to ≤100°C.