PURPOSE: To simplify the conductor plate and depolarization plate in the water electrolytic device provided with a feeder on both sides of a solid high molecular electrolyte by using the foamed metal and porous carbon of specified porosity having a gas and liq. passage function as the feeder.

CONSTITUTION: Catalytic electrodes 2 and 3 are joined to both surfaces of a solid high molecular electrolyte 1, and feeders 4 and 5 and terminal strips 6, 7 and 8 to supply an electric power to the feeders are arranged on both sides of the electrolyte. In this water electrolytic device, the foamed metal and porous carbon of 95% porosity having a gas and liq. passage function are used as the feeders 4 and 5. Consequently, the conductor plates 7 and 8 and depolarization plate 6 need not be grooved, and the structure of the water electrolytic device is simplified.