PURPOSE: To prevent the loss of power exactly and easily by eliminating the residence of gas emitting from electrodes during electrolysis by providing a water- permeable partition wall such as to permit keeping a small aperture between electrode and filler on the periphery of electrodes.

CONSTITUTION: The inside of the electrolytic bath 1 is provided with the anode 2 and the cathode 3, and the periphery of at least one electrode is provided with the partition wall 4 with bubbles-permeable small apertures through which liquid to be treated can pass but not for filler. And, the filler layer 5 of formed on the outside of the partition wall.