PURPOSE: To provide an inexpensive baking furnace which has fast temperature rising and falling speeds, a small energy consumption in a high temperature holding state, can accurately control a temperature at the time of falling the temperature, and obtain uniform temperature in the furnace.

CONSTITUTION: A furnace body 22 is formed of an inner insulation layer 23 and an outer insulation layer 24, and cooling air is fed into a space forming member 32 for forming a space 25 to the body at the time of falling a temperature to lower the temperature of the body 22. A heat transfer member 33 connected to the member 32 to transfer heat of the member 32 to the air is provided in the space 25. The heat of a baking space 9 in the body 22 is transferred from the layer 23 to the member 33 in the member 32 through the member 32. When the air is introduced into the space 25 at the time of cooling the body 22, the heat in the body 22 is transferred to the air to be brought to the exterior to cool the body 22.