NOVELTY - The apparatus (25) has a photoelectric conversion unit (2) which includes a light-receiving surface and a back surface of light-receiving surface. The electrolysis electrodes (7,8) formed on back surface of conversion unit is immersed in an electrolytic solution. The electrodes is adapted to electrolyze the electrolytic solution by the EMF generated upon receiving the light of conversion unit to produce first and second gas respectively. The circuits providing EMF is switched to first external circuit and both electrolysis electrodes by a switching unit.    USE - Solar cell integrated gas manufacturing apparatus for supplying electric power to external circuit using solar cell.    ADVANTAGE - The EMF produced when photoelectric conversion unit receives light can be supplied to first external circuit and electrodes by switching unit and can be utilized more efficiently. Since the electrolysis electrode are provided in the back surface of the photoelectric conversion unit, the light can be entered in the light-receiving surface of the conversion unit without electrolyte solution, so that the absorption and scattering of the incident light by the electrolyte solution can be prevented, thus the quantity of the incident light supplied to the conversion unit is increased and optical efficiency is made high. The wiring resistance between the conversion unit and electrodes can be made low and the gases can be manufactured efficiently, when electrodes are provided in back surface of the conversion unit. The installation area can be decreased, as the solar cell and gas manufacturing apparatus are integrated and set as compacter apparatus. The manufacturing cost is reduced, as the common unit is used for solar cell and gas manufacturing apparatus.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the solar cell integrated gas manufacturing apparatus.    Photoelectric conversion unit (2)    Electrolysis electrodes (7,8)    Back substrate (14)    Electrolyte solution chamber (15)    Solar cell integrated gas manufacturing apparatus (25)