An optical fiber can efficiently excite metallic ions by a pump lightwave, and an optical fiber amplifier and an optical fiber laser light source both incorporate the optical fiber. The optical fiber comprises (a) a solid region that has a first region doped with metallic ions and a second region surrounding the first region and that allows a lightwave for exciting the metallic ions to travel in a multiple mode and (b) a third region surrounding the second region and having a plurality of holes stretching along the length of the optical fiber. The optical fiber has a structure in which the first region is supplied with the power of a lightwave that is included in the pump lightwave and that is in a mode having no intensity peak at the center axis of the solid region.