PURPOSE: To recover oil in liquid with high rate of recovery by passing oil-contg. liquid between confronting electrodes impressed by a voltage and breaking electrostatic binding of the water in the liquid with the oil in the liquid.

CONSTITUTION: Oil-contg. liquid sucked from a suction port 2 by a pump 1 into an electrode cell 3 passes between confronting electrodes 3a, 3b impressed by a DC, AC, or pulsating current. Electrostatic binding of the water with the oil contained in the liquid is broken during passage between the electrodes 3a, 3b to cause separation into original oil and water. The oil is attracted by the anode to aggregate to one body and floats up on the surface of water in an oil recovering tank 4; the floated oil is recovered by a pressure valve 5, etc. Residual oil, metal ion, or organic matters contained in the water separated from oil and recovered by the oil recovering tank 4, when it is reutilized, is ionized or depolarized in a second electrode cell 6. and such contaminant is removed by attracting electrostatically in an attraction tower 7.