Disclosed is a hydrogen generation device (100) comprising: a transparent substrate (1); a photocatalyst electrode (4) arranged on the transparent substrate (1) and composed of a transparent conductive layer (2) and a photocatalyst layer (3); a counter electrode (8) electrically connected to the transparent conductive layer (2); an electrolytic solution layer arranged between the photocatalyst electrode (3) and the counter electrode (8) and containing water; a separator (6) for dividing the electrolytic solution layer into a first electrolytic solution layer (5) that is in contact with the photocatalyst electrode (4) and a second electrolytic solution layer (7) that is in contact with the counter electrode (8); a first gas outlet (14) for removing a gas generated in the inside of the first electrolytic solution layer (5); and a second gas outlet (15) for removing a gas generated in the inside of the second electrolytic solution layer (7). The photocatalyst electrode (4) and the counter electrode (8) are so arranged that the surface of the photocatalyst layer (3) and the surface of the counter electrode (8) face each other. The separator (6) is so adapted that an electrolyte contained in the electrolytic solution layer can permeate through the separator (6) and a hydrogen gas and an oxygen gas contained in the electrolytic solution layer cannot permeate through the separator (6).
