A heat exchanger heat-utilization device is obtained that can efficiently store heat and dissipate heat in or from a chemical thermal storage medium, and a manufacturing method of the heat exchanger heat-utilization device. A heat exchanger heat-utilization device includes: chemical thermal storage medium composite molded formed by organizing chemical thermal storage medium particles into a porous structural body having flow channels; and a heat exchanger body. The heat exchanger body has thermal storage medium containing portions in which the chemical thermal storage medium composite molded bodies are accommodated, and fluid flow channels that are partitioned from the thermal storage medium containing portions by partition walls and through which a heat exchange medium flows for heat exchange with the chemical thermal storage medium composite molded bodies.