To remove oil and reduce the volume of an oil residual container in which oil is left behind by providing a pressurization chamber surrounded by a closable lid part and having a shielding wall, pressing the container to be treated by a hydraulic ram while holding the container with wall surfaces opposite to each other in the pressurization chamber, which leads the dripping oil into an oil receiving tank and a chute which leads the volume-reduced container to a volume-reduced container receiver.

A slide door 15 is opened, and an oil filter to be treated is placed in a container receiver 21. When the slide door 15 is closed, a sensor 16 is operated, a hydraulic unit 28 is started, and a hydraulic ram 17 is advanced by a hydraulic cylinder 18. The oil filter stored in a pressurization chamber 14 is held, compressed and squeezed by the hydraulic ram 17 and a pressure receiving plate 19, and the oil to be discharged is passed through an oil conduit 20 and a drop port 22, and discharged into an oil receiving tank 25. The oil filter which is freed by the retraction of the hydraulic ram 17 is dropped from the drop port 22, slides on a chute 27, and enters a volume-reduced container receiver 26. The scattered oil is stored in the pressurization chamber 14, preventing an external part from being polluted with oil.