A method for manufacturing optical fiber preform comprising a core glass containing a light emitting substance (e.g. rare earth metal dopant) and a cladding glass, easily controlling an amount of the light emitting substance incorporated into the core glass without requiring any complicated step, includes the steps of forming a porous layer made of a precursor of the core glass on an inner surface of a hollow tube having an inner surface made of the cladding glass, spraying a medium containing the light emitting substance onto the porous layer, forming a layer of the core glass containing the light emitting substance by sintering the porous layer containing the light emitting substance, and forming a preform rod by collapsing the obtained hollow tube into a solid article. Alternatively, another method according to the invention includes the steps of spraying a medium containing a precursor of the core glass on the inner surface of the hollow tube, forming the core glass layer by sintering the formed precursor layer, and forming a preform rod by collapsing the obtained hollow tube into a solid article. A third method comprises spraying sequentially core-forming material and light emitting substance and a fourth method simultaneous spraying of both. An optical fiber can be formed by drawing the thus obtained optical fiber preforms.