There is provided an electrolysis gas converter, which prevents excessive gas generation and can maintain a constant amount of gas conversion even if outside air conditions such as humidity changes. The converter, which provides DC current to a jointed electrochemical device 8 comprising a solid polymer electrolytic film 3 between an anode 1 and a cathode 2 having a catalytic layer on a base substrate of conductive porous material, comprises means 11 and 17 which provide a fixed current to the jointed electrochemical device 8.