Abstract: Workpieces are disposed between a pair of side walls in a heat treatment chamber. A centrifugal fan is disposed to face the workpieces inside the heat treatment chamber, and sucks gas from the workpiece side and generates air current. In regions at the respective side wall sides relative to an intermediate position between the pair of side walls, an air current regulation unit regulates the air current so as to restrict flows of the air current from the centrifugal fan to the respective side wall sides when a rotary blade of the centrifugal fan rotates in regions in which outer circumferential edge portions of the rotating rotary blade separate from the respective side walls, and allows the flows in regions in which the outer circumferential edge portions of the rotating rotary blade approach the respective side walls.

Abstract: A heater is provided to heat a metallic workpiece as a heating treatment target. In a heat treatment chamber, the heater and the workpiece are disposed. A shielding member is disposed between the heater and the workpiece inside the heat treatment chamber, and provided to be capable of shielding radiation of radiation heat from the heater to the workpiece.

Abstract: Workpieces are disposed between a pair of side walls in a heat treatment chamber. A centrifugal fan is disposed to face the workpieces inside the heat treatment chamber, and sucks gas from the workpiece side and generates air current. In regions at the respective side wall sides relative to an intermediate position between the pair of side walls, an air current regulation unit regulates the air current so as to restrict flows of the air current from the centrifugal fan to the respective side wall sides when a rotary blade of the centrifugal fan rotates in regions in which outer circumferential edge portions of the rotating rotary blade separate from the respective side walls, and allows the flows in regions in which the outer circumferential edge portions of the rotating rotary blade approach the respective side walls.