To continuously dry a processing object such as dried food in a high quality by arranging a preheating means of the processing object, an oil tank to store a heater oil liquid and a net conveyor to circularly transfer the processing object while soaking it in the oil tank, in a vacuum vessel, and connecting a deoiling means to the vacuum vessel.

A processing object inputted to an input part 3 from a carrying-in conveyor 4 drops on a seal part 2 together with an oil liquid injected into the input part 3 from an oil liquid injection nozzle 30, and is sent into a vacuum vessel 1 whose pressure is reduced by a rotary valve. Next, the processing object is preheated by an oil shower 19 after being inputted to a net conveyor 12 by being dispersed by a dispersing conveyor 18. After being soaked in an oil tank 10, it is inputted in a defiling machine 51 through a carrying-out conveyor 50, and the fat and oil content is defiled by the centrifugation action by a basket body 54. On the other hand, the oil liquid is recovered by an oil liquid gutter 24 together with an oil liquid overflowing from the oil tank 10, and is circularly used by being sent to an oil liquid tank 35 from an oil liquid recovering pipe 34.