A method for producing an optical fiber preform

According to the present invention is a method for producing an optical fiber preform comprising: an etchant gas flowing into the silica-based glass, while a continuous movement of the glass tube in the longitudinal direction of the heat source for heating the glass tube to corrosion comprising the step of etching the glass surface, the inner portion of the impurities. Maximum alkali metal concentration of the glass tube 500 atomic ppm to 20,000 atomic ppm, the highest chlorine atom concentration of 0 ppm to 1000 atomic ppm, and a maximum fluorine concentration of 0 atomic ppm to 10,000 atomic ppm. In the etching step, the maximum temperature of the outer surface of the glass tube in the range of 1900 deg.] C to 2250 deg.] C, and the heating time is set to be equal to or less than is given by the time, in minutes.