In a particle analyzing apparatus including a capillary for passing through a fluid containing particles to be analyzed, an optical system is employed to collect fluorescent light emitted from particles or substances labeled to the particles with improved collection efficiency preserving resolution of the instrument. The optical system may include a first collection lens attached to the capillary and a first reflection element arranged adjacent to the first collection lens configured to reflect fluorescent light of one or more wavelengths. The optical system may include a second collection lens attached to the capillary and a second reflection element arranged adjacent to the second collection lens configured to reflect fluorescent light of one or more wavelengths.