To provide a water and oil separation device which separates an aqueous component and an oily component and which dissociates the emulsion state formed of a solvent and washing water for recycling wastes, in order to maintain the best condition in the next printing by washing an ink roller and blanket after completing the series of printing in the off-set printing because the waste used in washing includes a mixture of ink, a solvent and water.

The water and oil separation device is comprised of a waste tank 2, a waste introduction pipe 8 where the waste is introduced from the upper part of the waste tank 2, an aqueous component discharge pipe 10 and an oil component discharge pipe 9, the aqueous component which has sedimented at the upper part within the waste tank 2, a buoy 22 of which the part enters into an emulsion of the boundary part with the oil component floated on the upper part and which floats in water and sinks in the solvent and an excitation unit 24 to impart oscillation to the emulsion layer 33 within the waste tank 2 by beating the outer wall of the waste tank 2 at the outside of the boundary part.