A laser microscope 1 includes: a filter unit 18, which is a fluorescence-splitting mechanism that splits the fluorescence generated by the specimen S and the excitation light according to a wavelength, and that changes a wavelength at which light is split; a diffraction grating 22 that disperses the fluorescence split by the filter unit 18; a mirror 23 that changes a wavelength of fluorescence that is detected by a PMT 26 and that is dispersed by the diffraction grating 22; and a control unit 30 that controls the filter unit 18. The control unit 30 performs control to change a wavelength at which the filter unit 18 splits light in accordance with a change in the wavelength of the fluorescence that is detected by the PMT 26 and that is dispersed by the diffraction grating 22, the change being performed by the mirror 23.