A fluorescence observation apparatus including a light source that radiates illumination light and excitation light a return-light-image generating portion and a fluorescence-image generating portion that generate a return-light image and a fluorescence image, respectively a fluorescence detecting portion that detects a fluorescence region in the fluorescence image a return-light-image adjusting portion that adjusts gradation values of the return-light image a superimposed-image generating portion that generates a superimposed image by using the return-light image, in which the gradation values have been adjusted, and the fluorescence image and a coefficient setting portion that sets, in the case in which the fluorescence region is detected, a degree-of-reduction of the gradation values, so that the gradation values of the return-light image are decreased as compared with the case in which the fluorescence region is not detected.
