To eliminate scanning with fluorescent detection optical system and to lower the manufacturing cost more than a prism.

A fluorescent light emitted from an emission point 6 is passes through a focus lens 32 to generate a parallel light and only specific wavelength components pass through spectral filters 34a-34d, respectively. The fluorescent light of different wavelength are reflected, respectively, on mirrors 38a-38d at different angles and impinge on different parts of a focus lens 40 thus focusing an image on a two-dimensional detector 42. Since a plurality of emission points 6 are generated in the direction vertical to the plane of paper, the fluorescent light is detected simultaneously for the plurality of emission points and an image shown at C is detected on the detector 42.