Provided is an artificial-photosynthesis module, which decomposes an aqueous electrolyte solution into hydrogen and oxygen by means of light, including a photoelectric conversion unit that receives light to generate electrical energy; a hydrogen gas generating part that decomposes the aqueous electrolyte solution, using the electrical energy of the photoelectric conversion unit, and generates hydrogen gas; and an oxygen gas generating part that decomposes the aqueous electrolyte solution, using the electrical energy of the photoelectric conversion unit, and generates oxygen gas. The photoelectric conversion unit, the hydrogen gas generating part, and the oxygen gas generating part are electrically connected in series, and the hydrogen gas generating part and the oxygen gas generating part are arranged within an electrolytic chamber to which the aqueous electrolyte solution is supplied. The hydrogen gas generating part has an inorganic semiconductor film having a pn junction.