Disclosed is a dry CO2 capturing device with improved energy efficiency, which utilizes a difference in temperature between a regeneration operation of isolating CO2 from an sorbent containing CO2 absorbed therein and a pre-treatment operation of allowing H2O to be adsorbed to CO2. The dry carbon dioxide (CO2) capturing device, includes a recovery reactor for recovering CO2, a recovery cyclone for discharging a gas while separating the CO2-captured solid sorbent only, a regenerator for receiving the CO2-captured solid sorbent and separating CO2 captured in the solid sorbent, and a pre-treatment reactor for cooling the solid sorbent free from CO2, wherein a first heat exchanger is provided between the recovery cyclone and the regenerator to pass the CO2-captured solid sorbent therethrough, and a second heat exchanger is provided between the pre-treatment reactor and the regenerator to pass the solid sorbent free from CO2 therethrough. The first and second heat exchanger include a first and second heat exchange jacket mounted thereon which are connected to each other in a closed loop state.