PURPOSE: .To enable shortening of a batch operation cycle by making a time lag where a temperature of a main body and that of a chip become identical with each other, by feeding a medium heating or cooling directly the chip in a vacuum rotary dryer into the main body.

CONSTITUTION: Both ends of a main body 1 of dryer is supported by a main body bearing 8 and turned. They are provided with an exhaust pipe 10 and connected by piping with an ejector 5. A heating medium is circulated within a system by making use of a heating medium pump 2 and supplied to the main body 1 of the dryer through a heating medium heater 3 at the time of heating and a heating medium cooler 4 at the time to cooling. When N2 piping 7 is connected with a heating medium piping 6 and solidified with heat transfer cement, a temperature of N2 gas becomes identical with that of the heating medium. The N2 gas to be supplied into the main body of the dryer accelerates polymerization reaction by depressurizing the inside of the main body by actuating the ejector by suspending the dryer at the time of arrival of a temperature a chip of at a steady temperature. Therefore, as the time for a temperature rise and temperature fall of the chip of contents can be shortened an operation cycle can be shortened. Then operation control becomes easy because operation can be performed by controlling the temperature of the heating medium.