PURPOSE: To suppress the fluctuation in outer diameter of optical fiber in a short period, and reduce the deviation of the fiber in diameter, by setting a damping material between the rod catcher holding the rod in the preform and the driving motor.

CONSTITUTION: Rod catcher 5 is allowed to hold the glass supporting rod 4 to which the preform 3 is fused, and is fixed to the rod catcher plate 8 through a damping rubber sheet 11 for absorbing the vibrations from the motor 7. In the meantime, the roller plate 9 to which the rod-holding roller 6 is fitted is set through a plurality of damping rubber sheets 12 to the roller plate holder 10 whereby the transmission of the vibration of the motor 7 to the rod 4 is stopped. The unit provided with the damping means is used to driving the motor 7 to send the preform 3 at a constant speed into the heater 2 in the oven 1 to melt the free end of the preform and draw the glass fiber at a high speed of over 200m/min.