Provided is a method of manufacturing an optical fiber preform from which an optical fiber having the desired characteristics can easily be produced. The method comprises the steps of: (1) preparing an intermediate preform for manufacturing an optical fiber preform; (2) measuring a refractive index profile in a radial direction at each of a plurality of positions in the longitudinal direction of the intermediate preform; (3) demarcating the outer diameter shape of the intermediate preform based on the result of the step of measuring the refractive index profile so that an optical fiber preform can be manufactured such that an optical fiber having the desired characteristics may be produced from the optical fiber preform; (4) elongating the outer periphery of the intermediate preform so that the outer diameter shape may be formed as demarcated in the step of demarcating the outer diameter shape; and (5) drawing, so as to have a substantially constant outer diameter, the intermediate preform that has been subjected to the grinding step.