To provide an endoscope system that includes a light source, an insertion part to be inserted into a living organism for guiding a illumination light emitted from the light source and a light returned from the living organism, a deflection optical system for outwardly directing the illumination light in a radius direction of the insertion part and for introducing a light inwardly returned from the living organism in the radius direction into the insertion part, a part for capturing the returned light, a part for detecting an insertion speed of the insertion part, a part for adjusting a frame rate for the image capturing of the image capturing part based on the detected insertion speed, an image forming part for arranging acquired images at a pitch based on the insertion speed to form an image of the inside of the living organism, and a part for displaying the formed image.