Provided are a power generation system which does not limit a patients range of motion, is harmless to a living body, and can obtain a sufficient electricity generating capacity in the stomach or the intestines and a disposable medical capsule device which does not have to be collected after use. A power supply system is mounted in the capsule device, comprises an electrode pair including at least two electrodes provide on an outer wall surface of a capsule main body, for example, an aluminum electrode and a catalyst-supporting carbon electrode, generates power when immersed in an electrolytic solution consisting of gastric juice or intestinal juice, and supplies the power to constituent portions in the capsule device.
