An endoscope apparatus 1 includes a light source device 4, an endoscope 3, a processor 7, and an observation monitor 5. The light source 4 device switches between excitation light EX that excites a connective tissue in a submucosa of a tissue within a body cavity, narrow-band light NBa absorbed by a blood vessel 64 running through the submucosa 62 or muscularis propria 63, and narrow-band light NBb absorbed by a substance locally injected into the submucosa 62, and radiates the selected light. The processor 7 generates a plurality of image signals, images of which are picked up by a CCD 2 of the endoscope 3 and the observation monitor 5 synthesizes a plurality of images and displays the synthesized image.
