A monopolar membrane-electrode assembly includes an electrolyte membrane with a plurality of cell regions, an anode supporting body and a cathode supporting body on both sides of the electrolyte membrane, respectively having a plurality of apertures corresponding to the cell regions, a plurality of anode and cathode current collectors, each including a current collecting portion to correspond to each aperture of the respective anode or cathode supporting body to collect current, a conducting portion connected to a side of the current collecting portion, and a connecting line that connects the conducting portion to an outside terminal, a plurality of anode and cathode electrodes respectively formed on the and the cathode current collecting portions, and a circuit unit connected to the connecting lines of the anode current collectors and the cathode current collectors, wherein the cells are connected in series or parallel, or electrically separated through the circuit unit.