Abstract: In the manufacturing of optical fiber preform with excellent accuracy of outer diameter made of the rod as drawn from synthetic quartz ingot, the outer diameter measuring devices 67 and 68 measure the outer diameters of the cone 2 and rod 3 drawn from the ingot 1, and the drawing speed is controlled based on the measured outer diameters. The optical fiber preform manufacturing apparatus that finishes the rod into truly round form without any curve has a rotary holding means 13 and 14 that hold the rod 3 resulting from the heating and drawing of the ingot 1 rotating it in synchronization with the rotation of the ingot 1, a comparison device 18 that outputs a signal after comparing the outer diameter of the cone 2 as measured by the outer diameter measuring device 11 with that of the referential circle, a control device 19 that controls the rotational amount of the rotating device 10, and a control device 20 that controls the rotational amount of the rotary holding device 13 and 14.