An endoscope apparatus includes an illumination apparatus that applies first and second narrow-band light having different peak wavelengths to a subject, an imaging device that acquires image light from the subject with pixels to generate an acquisition image signal, and an image processing circuit. The image processing circuit includes a storage that has stored assumed subject types including information about a wavelength range of assumed subjects, and a subject type decision circuit that decides an assumed subject type for part of the pixels based on a first image signal about the first narrow-band light, a second image signal about the second narrow-band light, and the assumed subject types. The image processing circuit constructs a display image signal based on the acquisition image signal and decided assumed subject type.