To provide a method for detecting the degradation degree of amine liquid, which monitors the concentration of a thermostable acid component in an amine liquid and accurately and quickly detects the degradation degree of amine liquid by a simple constitution and operation, a method and an apparatus for recovering an amine liquid by the method.

In order to detect the degradation degree of an amine liquid in which an acidic gas is absorbed in an absorption tower 1 and which is recovered by a recovering tower 2, a sample is diluted by a dilution apparatus 21 of a degradation degree detection apparatus 20, is decationized by a decationization apparatus 22, a thermally decomposable acid component is removed by a deaeration apparatus 23 and electric conductivity is measured by an electric conductivity measurement apparatus 24 to detect the degradation degree. In order to secondarily recover an amine liquid to be treated by the result, an amine purification chamber 15 is formed between a bipolar membrane 13 and an anion-exchange membrane 14 arranged between a minus terminal 11 and a plus terminal 12, an acid concentration chamber 16 is formed at the plus terminal 12 side of the anion-exchange membrane 14, the amine liquid to be treated is introduced into the amine purification chamber 15, the purified amine liquid is taken out from the amine purification chamber 15 and a concentrated acid liquid is taken out from the acid concentration chamber 16.