Heat treatment apparatus

A heat treatment apparatus using heat exchange between a first fluid and a second fluid, the apparatus comprising:

• a heat exchange unit including a plurality of first channels through which the first fluid flows and a plurality of second channels through which the second fluid flows;
• a space-forming part having a space facing channel openings of the respective first channels;
• a first opening located in the space-forming part and having a first aperture;
• a flow-regulating part installed in the space in the space-forming part to regulate a flow of the first fluid;
• and
• an attachment part for removably attaching the flow-regulating part through the first aperture,
• wherein the space in the space-forming part is a space in which the first fluid led out of the respective channel openings flows together, or a space from which the first fluid flowing together is introduced to the respective channel openings, and
• in a state in which the flow-regulating part is fixed in the space-forming part, the flow-regulating part is opposed to the plural channel openings.