Optical fiber glass preform manufacturing method

A method of manufacturing an optical fiber glass preform, the method comprising:

• depositing glass particles on a base material, the glass particles being generated by glass making feedstock gas being supplied while a burner and the base material that is rotating are reciprocated relatively to each other, wherein
• when a portion corresponding to an outer diameter equal to or more than 0.80 L and equal to or less than L is deposited, wherein L represents a final outer diameter of a part of the optical fiber glass preform manufactured, the part being formed by the deposition of the glass particles, the deposition to be performed is selected from among:
• a first condition where an angle formed by a first line extending from a center O of a cross section of the base material to a rotational position r0 at which one round trip of the relative reciprocation starts and a second line extending from the center O to a rotational position r1 at which the one round trip of the relative reciprocation ends is an angle excluding 0°, 120°, 240°, 72°, 144°, 216°, and 288°;
• a second condition where the angle is 120° or 240°, thereby to deposit the glass particles to a thickness corresponding only to a thickness equal to or less than 0.02 L;
• a third condition where the angle is 72°, 144°, 216°, or 288°, thereby to deposit the glass particles to a thickness corresponding only to a thickness equal to or less than 0.03 L;
• a fourth condition where the angle is 0°, thereby to deposit the glass particles to a thickness corresponding only to a thickness equal to or less than 0.01 L, and
• a fifth condition where the angle is 180°, thereby to deposit the glass particles to a thickness corresponding only to a thickness equal to or less than 0.02 L, and the deposition under the selected condition is performed.