To reduce the time required for degreasing while the generation ratio of defects accompanying the rapid rise in the temperature of a work is reduced.
The inside of a furnace body 1 is provided with temperature sensors 7a, 7b for measuring atmospheric temperature, and first and second temperature sensors 7c, 7d for measuring the temperature of a work W. A controller 10 judges that the rapid increase in the temperature of the work W is arisen based on the temperature difference between the atmospheric temperature measured with temperature sensors 7a, 7b and the surface temperature of the work W measured by the temperature sensors 7c, 7d, and suppresses the rapid rise in the temperature of the work W by the control of the pressure in the furnace body, the control of the concentration in oxygen or cooling with cooling gas.
YOSHIDA HIROYUKI
Atsuo Mori