TECHNOLOGY FOCUS - ELECTRONICS - Preferred Water Electrolysis System: The water electrolysis system further comprises a water circulation apparatus for circulating the water stored in the water storage apparatus through the water electrolysis apparatus. It further comprises a water supply apparatus for supplying the water to the water storage apparatus, where the water storage apparatus includes a water level detector for detecting a water level in the tank in comparison with a predetermined level, and the water supply from the water supply apparatus to the water storage apparatus is controlled based on a detection signal from the water level detector. The water storage apparatus includes a lower limit water level detector for detecting the water level in the tank in comparison with a predetermined lower limit level, and operation of the water electrolysis apparatus is stopped based on a detection signal from the lower limit water level detector. The water storage apparatus also includes a partition wall member disposed in the tank, and an upper end of the partition wall member is positioned above a predetermined higher limit level in the tank. The tank includes: (i) a water return outlet for returning the water in the tank to the water electrolysis apparatus through the water circulation apparatus; and (ii) a discharge outlet for discharging a separated gas component, and where a lower opening is formed in a lower portion of the partition wall member and is in communication with the water return outlet, and an upper opening is formed around an upper portion of the partition wall member and is in communication with the discharge outlet. Partition wall members are also provided in the system. The water electrolysis system comprises: (a) a water electrolysis apparatus including current collectors and an electrolyte membrane disposed in between for electrolyzing water, thus generating oxygen at an anode side and generating hydrogen at a cathode side; (b) a water storage apparatus for separating between the oxygen and residual water discharged from the water electrolysis apparatus, thus storing the water; and (c) a water circulation apparatus for circulating the water stored in the water storage apparatus through the water electrolysis apparatus, where the water storage apparatus includes a tank for storing the water, an inlet for introducing the oxygen and the residual water discharged from the water electrolysis apparatus into the tank, and a water return outlet for returning the water in the tank through the water circulation apparatus to the water electrolysis apparatus, and the inlet is positioned below the water return outlet. A partition plate is formed in the tank to prevent the oxygen and the hydrogen introduced from the inlet into the tank from being sucked into the water return outlet.