Abstract: While a large number of positive and negative electrodes are alternately arranged in an alignment on a same level in an electrolytic tank, a pair of magnets having the polarities thereof fixed in the same direction and which are disposed along the direction horizontally orthogonal to the arrangement of the electrodes of the same level, so that an electric field and a magnetic field will be generated on the horizontal directions orthogonal to each other and a force according to the Fleming's left-hand rule will be directed to the upward direction perpendicular to both the electric field and the magnetic field. The small bubbles adherent to the surface of the electrodes are enabled to be separated therefrom and allowed to float up owing to the addition of the upward force to their insufficient buoyancy.