A CO2 recovery unit includes a CO2-absorber that causes a gas containing CO2 to contact a CO2-absorbing solution and that causes the CO2 in the gas to be absorbed into the CO2-absorbing solution; a CO2-regenerator that heats the CO2-absorbing solution, releases the CO2 from the CO2-absorbing solution, and regenerates the CO2-absorbing solution; and a CO2 recovery amount controller that: calculates a computed target value of a CO2 recovery amount and a computed target value of a CO2 recovery rate based on a set value of the CO2 recovery rate, actual measured values of CO2 concentration, gas flow rate, and temperature of the gas, and calculates a maximum value of the CO2 recovery amount in the CO2-absorber and a maximum value of the CO2 recovery amount in the CO2-regenerator.