Provided are a reclaimer 51 that introduces, through a branch line L 11 , and stores a part 17a of an absorbent 17 regenerated in a regenerator of a recovery unit that recovers CO2 or H 2 S in a gas, a first alkaline agent supply section 53A that supplies an alkaline agent 52 to the reclaimer 51, a heating section 54 that heats the absorbent 17 stored in the reclaimer 51 and to which the alkaline agent 52 has been mixed to obtain recovered vapor 61, a first vapor cooler 55A that cools the recovered vapor 61 discharged from the reclaimer 51 through a vapor line L 12 , a first gas-liquid separator 56A that separates a coexisting substance 62 entrained in the cooled recovered vapor 61 into a recovered absorption agent vapor (gas) 17b and the liquid coexisting substance 62 by gas-liquid separation, and an introduction line L 13 that introduces the recovered absorption agent vapor 17b separated in the first gas-liquid separator 56A into a regenerator 20.