The present invention relates to an optical amplifier module, or the like, having a structure for enabling effective suppression of photodarkening and efficient optical amplification. The optical amplifier module comprises a first optical amplification waveguide which is comprised of a phosphate glass as a main component and includes a ytterbium-doped first optical waveguide region, a second optical amplification waveguide which is optically coupled to the first optical amplification waveguide and includes a ytterbium-doped second optical waveguide region which is co-doped with aluminum, and pumping light source units which supply pumping light respectively to the first optical amplification waveguide and the second optical amplification waveguide. The light to be amplified, having inputted to the first optical amplification waveguide, is amplified only once by means of the pumping light, in each of the first optical amplification waveguide and the second optical amplification waveguide.