In a hydrogen producing device, an electrolyte flow path between a plurality of hydrogen producing cells is disposed in a hydrogen production side and in an oxygen production side, separately. Further, an electrolyte flow path is formed through which the electrolyte flows downward from the top between the plurality of hydrogen producing cells, and on the other hand the electrolyte flows upward from the bottom within each hydrogen producing cell. Moreover, a contact point with a produced gas or an atmosphere is provided in a pathway of the electrolyte flow path.