Abstract: A microscope includes: an illumination optical system which irradiates a specimen with excitation light; a detector which detects fluorescence emitted from the specimen; and an observation optical system which guides fluorescence to the detector and includes: a first optical filter having wavelength reflection and transmission characteristics that vary depending on where light enters; a second optical filter disposed in an optical path of light reflected by the first optical filter, having a boundary wavelength of transmission changing with respect to a position along a first direction, and transmitting light having a wavelength longer than a first boundary wavelength at where the reflected light enters; and a third optical filter disposed in the optical path and having a boundary wavelength of transmission changing with respect to a position along the first direction, and transmitting light having a wavelength shorter than a second boundary wavelength at where the reflected light enters.