A body-insertable apparatus to be inserted into a subject includes an illumination unit that illuminates an inside of the subject； an imaging device having an effective pixel region that has a predetermined size and on which an optical image of the inside of the subject illuminated by the illumination unit is formed, and having an optical black region at which the optical image is shielded； and a light adjustment control unit that adjusts an amount of light from the illumination unit to the effective pixel region based on pixel values of the effective pixel region of an image signal and pixel values of the optical black region of the image signal.
