There is provided a hydrogen production device high in light use efficiency and capable of producing hydrogen with high efficiency.The hydrogen production device according to the present invention includes a photoelectric conversion part having a light acceptance surface and a back surface, a first gas generation part provided on the back surface, and a second gas generation part provided on the back surface, in which one of the first gas generation part and the second gas generation part is a hydrogen generation part to generate H2 from an electrolytic solution, another one thereof is an oxygen generation part to generate O2 from the electrolytic solution, the first gas generation part is electrically connected to the back surface, and the second gas generation part is electrically connected to the light acceptance surface via a first conductive part.