A capsule endoscope includes a capsule portion. The capsule portion includes at least an observation optical unit having an image pick-up element and an optical lens that forms an objective optical system, an illuminating unit having an illuminating substrate, an electroluminescence light source, and a light-emitting control circuit, a peripheral-circuit part which forms various circuits having a signal processing circuit, a receiving and transmitting circuit, and a control circuit, and a power source unit which supplies power to the observation optical unit, the illuminating unit, and the peripheral-circuit part.