A CO 2 recovery system comprising: an absorber including a CO 2 absorbing section and at least one water-washing section, the CO 2 absorbing section allowing flue gas to come into contact with a basic amine compound absorbent so that the basic amine compound absorbent absorbs CO 2 in the flue gas, the at least one water-washing section allowing the decarbonated flue gas in which an amount of CO 2 has been reduced in the CO 2 absorbing section to come into contact with wash water to reduce amounts of the basic amine compounds entrained in the decarbonated flue gas; a regenerator for releasing the CO 2 from the basic amine compound absorbent containing the CO 2 absorbed therein; and an absorbent-treating section disposed downstream of the at least one water-washing section through which the decarbonated flue gas flows, the absorbent-treating section allowing the decarbonated flue gas to come into contact with circulating acidic water to further reduce the amounts of the basic amine compounds entrained in the decarbonated flue gas the CO 2 recovery system further comprising a volatile organic compound treatment unit for reducing amounts of volatile organic compounds entrained in the decarbonated flue gas together with the basic amine compounds when the decarbonated flue gas is brought into contact with the acidic water into the absorbent-treating unit, and the CO 2 recovery system further comprising: a flue gas measuring unit for measuring a concentration of the volatile organic compounds in the decarbonated-deaminated flue gas in which the amounts of the volatile organic compounds and the amounts of the basic amine compounds have been reduced; and a control unit for adjusting a flow rate of the acidic water supplied to the volatile organic compound treating unit on the basis of the concentration of the volatile organic compounds measured by the flue gas measuring unit. an absorber including a CO 2 absorbing section and at least one water-washing section, the CO 2 absorbing section allowing flue gas to come into contact with a basic amine compound absorbent so that the basic amine compound absorbent absorbs CO 2 in the flue gas, the at least one water-washing section allowing the decarbonated flue gas in which an amount of CO 2 has been reduced in the CO 2 absorbing section to come into contact with wash water to reduce amounts of the basic amine compounds entrained in the decarbonated flue gas; a regenerator for releasing the CO 2 from the basic amine compound absorbent containing the CO 2 absorbed therein; and an absorbent-treating section disposed downstream of the at least one water-washing section through which the decarbonated flue gas flows, the absorbent-treating section allowing the decarbonated flue gas to come into contact with circulating acidic water to further reduce the amounts of the basic amine compounds entrained in the decarbonated flue gas the CO 2 recovery system further comprising a volatile organic compound treatment unit for reducing amounts of volatile organic compounds entrained in the decarbonated flue gas together with the basic amine compounds when the decarbonated flue gas is brought into contact with the acidic water into the absorbent-treating unit, and the CO 2 recovery system further comprising: a flue gas measuring unit for measuring a concentration of the volatile organic compounds in the decarbonated-deaminated flue gas in which the amounts of the volatile organic compounds and the amounts of the basic amine compounds have been reduced; and a control unit for adjusting a flow rate of the acidic water supplied to the volatile organic compound treating unit on the basis of the concentration of the volatile organic compounds measured by the flue gas measuring unit. a flue gas measuring unit for measuring a concentration of the volatile organic compounds in the decarbonated-deaminated flue gas in which the amounts of the volatile organic compounds and the amounts of the basic amine compounds have been reduced; and a control unit for adjusting a flow rate of the acidic water supplied to the volatile organic compound treating unit on the basis of the concentration of the volatile organic compounds measured by the flue gas measuring unit.