An excitation light irradiating device irradiates excitation light to a measuring site. A fluorescence imaging device performs an imaging operation for detecting a fluorescence image formed with fluorescence, which has been produced from the measuring site when the excitation light is irradiated to the measuring site. An illumination device irradiates illumination light to the measuring site. An ordinary imaging device performs an imaging operation for detecting an ordinary image formed with reflected light of the illumination light. A controller controls such that the imaging operation for detecting the fluorescence image and the imaging operation for detecting the ordinary image are performed alternately, and such that an operation for throwing off accumulated electric charges is performed before the imaging operation of the fluorescence imaging device is performed and/or before the imaging operation of the ordinary imaging device is performed.