Provided is a heat treatment apparatus capable of being configured to be more compact.
A heat treatment apparatus 1 includes a coolant passage defining body 42 to define a coolant passage 48 to supply a coolant to a workpiece 100. The coolant passage defining body 42 includes an upper member 50 and a lower member 40 as a plurality of coolant passage defining members, and is configured so that, by displacing these members 49 and 50 so as to approach each other along an up-down direction Z1 crossing a conveyance direction, the coolant passage 48 is defined in a state housing the workpiece 100. In addition , the coolant passage defining body is configured so that, by displacing the members 49 and 50 described above so as to separate from each other along the up-down direction Z1, the workpiece 100 is allowed to be let into and out of the coolant passage 48 along the conveyance direction A1.