PURPOSE: To reduce heat losses at the time of feed and takeout of parts for shrinkage fit and improve uniformity of temperature in a furnace and temperature-rising characteristics.

CONSTITUTION: A feed port 4 for a magazine 1 accommodating parts 2 for shrinkage fit is provided on the front surface near the upper end of a heating furnace 3 and a takeout port 5 for the magazine 1 is provided on the front surface near the lower end of the furnace 3. There is provided a door 8 which moves along the surface of the furnace 3 to open and close the port 4 and the port 5. A guide 14 is provided in the furnace 3 to form a transfer passage which allows a magazine 2 fed into the furnace from the port 4 to slide down toward the port 5. There is provided a pusher 24 which is usually positioned outside the furnace and runs into the furnace, when the port 5 is opened, to push and move the magazine 1 positioned at the lower end of the transfer passage to the outside, whereby uniformity of temperature in the furnace and temperature-rising characteristics can be improved, while uneven heating of the parts 2 for shrinkage fit is being avoided.