A fluorescence observation method of the present invention for detecting plural types of fluorescence emitted from two or more kinds of fluorescent molecules includes: subjecting each of the two or more kinds of fluorescent molecules to multi-photon excitation by exciting light having an exciting wavelength equal to or shorter than 700 nm in a visible region, to generate fluorescence upon making use of an absorption wavelength band in a deep ultraviolet region of each of the two or more kinds of fluorescent molecules; and simultaneously detecting plural types of fluorescence generated on a shorter-wavelength side or on both of the shorter-wavelength side and a longer-wavelength side of the exciting wavelength of the exciting light.