An endoscope apparatus includes: a light source portion that irradiates an excitation light and a reference light alternately; an image pickup portion that picks up images of the fluorescence from the living tissue and the reflected light; a signal processing portion that generates image signals from picked up signals; an addition processing portion that generates, from image signals of fluorescence, addition processed signals of fluorescence in which pixels are added; a light quantity control portion that controls the quantity of light so as to maintain a predetermined light quantity ratio between the quantities of the excitation light and the reference light from the addition processed signals of fluorescence and image signals of the reflected light; and a superimposition processing portion that superimposes the addition processed signals and the image signals of the reflected light, with the predetermined light quantity ratio being maintained.