PURPOSE: To reduce a heating or cooling time by mounting heat pipes to iron plates disposed between objects to be treated thereby making the temp. distributions in a vacuum tank uniform.

CONSTITUTION: A titled device is formed of a vacuum tank 3, heating or cooling sources disposed in the inside wall of the tank, plate members 11 disposed between the objects to be treated and heat pipes 12. Said heating sources are platelike heaters 13 and the cooling sources are refrigerant pipes. The pipes 12 are secured with good thermal contact on the surfaces of the materials 11 which are bent at a right angle in the end parts, along the surfaces thereof, and the end parts of the pipes are disposed near the heating or cooling sources. With such device, the heating or cooling time of the objects to be treated is reduced.