Sensitivity is increased by enhancing the fluorescence collection efficiency while suppressing the increase in size of an objective lens. An objective lens 17 is structured to have a convex lens part 26 in a center portion and to have a truncated conical cylindrical body 27 around the convex lens part 26. Therefore, a fluorescence component b having too wide an emission angle to fit in the convex lens part 26, of fluorescence emitted from a sample 16, can be collected by total reflection on an outer peripheral surface 27b of the cylindrical body 27. Thus, even light having too wide an emission angle to be collected by a normal convex lens can be collected. As a result, it is possible to suppress the increase in size of the objective lens, to enhance the fluorescence collection efficiency, and to prevent the S/N ratio from being decreased by the existence of undetected fluorescence that is blocked by a prism 20. This can realize a fluorescence information reading device having high sensitivity.