In the related art, CO2 recovery apparatuses that recover CO2 exhausted from boilers or the like of thermoelectric power plants are suggested (for example, refer to PTL 1). In the CO2 recovery apparatuses, after an exhaust gas is introduced into a CO2 absorption tower and a CO2 absorbing liquid is brought into contact with CO2 contained in the exhaust gas to absorb CO2, the CO2 absorbing liquid that has absorbed CO2 is introduced into a regeneration tower and is decarboxylated, and a high-concentration CO2 gas is recovered therefrom.