A hydrogen production device comprising: a photoelectric conversion part having a light acceptance surface and a back surface; and a first gas generation part provided on the back surface; and a second gas generation part provided on the back surface via an insulation part, wherein one of the first gas generation part and the second gas generation part is a hydrogen generation part to generate H 2 from an electrolytic solution, and the other thereof is an oxygen generation part to generate O 2 from the electrolytic solution, at least one of the first gas generation part and the second gas generation part is plural, and the photoelectric conversion part is electrically connected to the first gas generation part and the second gas generation part so that an electromotive force generated by a light acceptance of the photoelectric conversion part is supplied to the first gas generation part and the second gas generation part, the first gas generation part is electrically connected to the back surface of the photoelectric conversion part, the second gas generation part is electrically connected to the light acceptance surface of the photoelectric conversion part through a first conductive part, the first conductive part includes a first electrode which is in contact with the light acceptance surface of the photoelectric conversion part, the insulation part is provided so as to cover the side of the photoelectric conversion part, the second gas generation part is provided so as to cover at least a part of the insulation part, the part covering the side of the photoelectric conversion part, and the second gas generation part is in contact with the first electrode. a photoelectric conversion part having a light acceptance surface and a back surface; and a first gas generation part provided on the back surface; and a second gas generation part provided on the back surface via an insulation part, wherein one of the first gas generation part and the second gas generation part is a hydrogen generation part to generate H 2 from an electrolytic solution, and the other thereof is an oxygen generation part to generate O 2 from the electrolytic solution, at least one of the first gas generation part and the second gas generation part is plural, and the photoelectric conversion part is electrically connected to the first gas generation part and the second gas generation part so that an electromotive force generated by a light acceptance of the photoelectric conversion part is supplied to the first gas generation part and the second gas generation part, the first gas generation part is electrically connected to the back surface of the photoelectric conversion part, the second gas generation part is electrically connected to the light acceptance surface of the photoelectric conversion part through a first conductive part, the first conductive part includes a first electrode which is in contact with the light acceptance surface of the photoelectric conversion part, the insulation part is provided so as to cover the side of the photoelectric conversion part, the second gas generation part is provided so as to cover at least a part of the insulation part, the part covering the side of the photoelectric conversion part, and the second gas generation part is in contact with the first electrode.