NOVELTY - A hydrogen generating apparatus including a cathode chamber (302) in which electrolyte solution (307) is held, an anode chamber (305) in which an electrolyte solution (308) is held, a solid electrolyte membrane (306), a cathode (301) and an anode (304) is prepared. Light having wavelength of 350 nm or less is irradiated with respect to anode arranged in the anode chamber. Water contained in electrolyte solution (308) is oxidized by power supply, water contained in electrolyte solution (307) is reduced, and hydrogen is produced.    USE - Manufacture of hydrogen.    ADVANTAGE - The hydrogen is efficiently produced.    DETAILED DESCRIPTION - A hydrogen generating apparatus including a cathode chamber in which electrolyte solution (307) is held, an anode chamber in which an electrolyte solution (308) is held, a solid electrolyte membrane interposed between the anode chamber and cathode chamber, a cathode provided in cathode chamber, and an anode provided in anode chamber is prepared. The anode is photochemical electrode which functions by light irradiation. The anode has undoped aluminum gallium nitride layer comprising region consisting of nitride semiconductor formed by laminating n-type gallium nitride layer to which aluminum gallium nitride of formula: AlxGa1-xN, where x is more than 0 and 1 or less, preferably more than 0 and 0.25 or less, and impurity element are added. At least one portion of aluminum gallium nitride layer surface is coated with metal microparticles or metal oxide fine particles. The cathode is in contact with electrolyte solution (307). The anode is in contact with electrolyte solution (308). The cathode is electrically connected through anode and conducting wire (311). An external power supply is not included between cathode and anode. Light having wavelength of 350 nm or less is irradiated with respect to anode arranged in the anode chamber. Water contained in electrolyte solution (308) is oxidized by power supply, water contained in electrolyte solution (307) is reduced, and hydrogen is produced.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of hydrogen producing apparatus.    Cathode (301)    Cathode chamber (302)    Anode (304)    Anode chamber (305)    Solid electrolyte membrane (306)    Electrolyte solutions (307,308)    Conducting wire (311)