A capsule endoscope includes: a light emitting unit; an imaging unit; an image signal processing unit; and a setting unit that controls the light emitting unit and the imaging unit to perform pre-exposure, measures at least one of a light emission time and a light emission intensity, sets the measured time or intensity for a main exposure process when the measured time or intensity is within a predetermined acceptable range, and sets at least one of the preset light emission time and light emission intensity for the main exposure process when the measured time or intensity is out of the acceptable range, wherein an acquisition process of an image is performed in accordance with the set light emission time or the set light emission intensity.