a method of manufacturing an optical fiber base material having very little impurity which deteriorates the transmission characteristic of an optical fiber is provided . the method of manufacturing an optical fiber base material including : producing a core member for the optical fiber base material by dehydrating and transparently vitrifying a base material formed by depositing glass particles ; and drawing the core member and then adding a cladding thereto at a desired core to cladding ratio , wherein the dehydrating includes suspending the base material in a furnace tube having a heating region in a first atmosphere at a first temperature , the base material passing through the heating region as upwardly moving , and the transparently vitrifying includes situating the base material below once and then allowing the base material to pass through the heating region in a second atmosphere at a second temperature as upwardly moving again .