An endoscope apparatus configured to acquire an image of an observation object includes a light source unit and an imaging system. The light source unit is configured to emit first and second narrow band light selected based on absorption spectra of first and second characteristic substances, respectively. The imaging system is configured to separately acquire first and second images by the first and second narrow band light, respectively. The apparatus further includes a characteristic substance region extractor configured to extract a characteristic substance region related to the first characteristic substance on the first image and/or a characteristic substance region related to the second characteristic substance on the second image.
