Abstract: The present invention relates to an optical fiber preform manufacturing method which can be used for wide band optical fibers by preventing the loss by OH-ions in the 1385 nm wavelength region by depositing a clad layer at a large thickness, so that the ratio of the outer diameter of a core to the outer diameter of a deposited clad is more than 2.5 after a collapse at the deposition of a clad layer and a core, and etching them respectively after the deposition and collapse, in order to prevent OH-ions contained in a tube and OH-ions penetrated into the surface by a hydrogen-oxygen burner from being diffused into the core in the deposition and collapse process in manufacturing an optical fiber preform by the MCVD method.