The image quality of fluorescent images of blood vessels obtained by imaging blood vessels emitting fluorescence is improved. Living tissue within a body cavity is imaged by an endoscope while fluorescent pigments within blood vessels are emitting fluorescence due to irradiation of excitation light. At this time, a standard observation image obtained by imaging the same portion of the body cavity while white light is being irradiated, and a fluorescent image obtained by imaging while the excitation light is being irradiated are obtained. A plurality of spectral images having different wavelength ranges are generated. The depth position of blood vessels within a region of interest are judged by a depth position judging unit. Thereafter, an image processing unit administers an image process using image processing conditions corresponding to the depth position of the blood vessels, and a processed image is displayed by a display device.
