A CO2 recovering apparatus includes a CO2 absorber that brings flue gas containing CO2 and O2 into contact with CO2 absorbing liquid to reduce CO2 in the flue gas; and a regenerator that reduces CO2 in CO2 absorbing liquid (rich solvent) that absorbed CO2 in the CO2 absorber to regenerate the CO2 absorbing liquid, so that the regenerated CO2 absorbing liquid (lean solvent) having CO2 reduced in the regenerator is reused in the CO2 absorber. A lower liquid reservoir is located at the bottom of the CO2 absorber, and an air-bubble gathering member is arranged therein to gather air bubbles included in the absorbing liquid.