Disclosed is an apparatus for stimulating living body including a light source unit which irradiates an optical signal for generating an electrical signal; a photovoltaic cell unit which generates an electrical signal using a received optical signal; and an electrode unit which stimulates living body using the electrical signal, wherein the photovoltaic cell unit and the electrode unit are implanted in the living body. The apparatus for stimulating living body may be manufactured in a flexible form, so that it may extend the range of choice for site to be implanted for the apparatus. Further, the adoption of the photovoltaic cell unit avoids the need of surgical operation for the change of battery.