To provide a device and method safely and easily conveying to a combustion furnace, a large amount of waste oil of petroleum belonging to the first class petroleum of low flash point and sludge.

This device is composed of: an open can chamber 10 receiving a sealable waste oil can 3 filled with waste oil and sludge; a can opening device 13 for boring a bottom portion by a can opening blade 13b while pressing a top portion of the waste oil can 3 by a press plate; a hopper 20 for storing the waste oil including the sludge extracted by the can opening device 13; an inactive gas supplying device 40 for supplying an inactive gas such as a nitrogen gas to control oxygen concentration in the open can chamber 10 and the hopper 20 to be at least lower than explosion limit oxygen concentration; and a force feed device 30 for conveying the waste oil including the sludge stored in the hopper 20 to the combustion furnace 50. At least the can opening blade 13b kept into contact with the waste oil can 3, the press plate 14, and the bottom plate 12 in the open can chamber, are made of copper alloy having an explosion-proof function.