Provided is a fluorescence reading device capable of narrowing a distance between a lens unit and an observation object to a distance according to a focal length of a refractive index distribution type lens and focusing fluorescence emitted from the observation object on detecting unit without blurring.Optical fiber sub-bundles equivalent to a light guide unit are buried in lens holding parts of a lens unit. Emission ends of the optical fiber sub-bundles are exposed to upper surfaces of the lens holding parts that face the observation object holding unit. The optical fiber sub-bundles guide the excitation light emitted from the light source and radiate the guided excitation light toward the surface of an observation object that faces the lens unit.