A gas production apparatus is provided which includes: a module including a plurality of PN junctions connected in series to one another, each being formed of an inorganic semiconductor and having a light receiving surface; two gas generators that are provided at open ends of PN junctions at both extremities of the module, respectively, on a side of the light receiving surface; an electrolysis chamber which contains an aqueous electrolytic solution in contact with the two gas generators and contains gases generated by the two gas generators; and a diaphragm which is ion-permeable but gas-impermeable, and partitions the electrolysis chamber into two regions including the two gas generators, respectively, and containing hydrogen and oxygen, respectively.