A reclaiming method is disclosed including conducting evaporation by introducing a part of the absorbent to recover CO2 or H2S in a gas in a closed system recovery unit and separating a degraded substance contained in the absorbent from the absorbent to be introduced into an evaporator and obtain recovery steam containing an absorbent and CO2 or H2S by a heating section that is provided on a circulation line that circulates in the evaporator; and removing ionic degraded substance by cooling the concentrate obtained in the evaporation and removing an ionic degraded substance in the concentrate after the cooling, wherein a purified concentrate from which the ionic degraded substance has been removed is reused as a purified absorbent.