To provide the subject device capable of efficiently operating a regenerating column for an absorbing solution, optimizing the operation and reducing a treating cost.

This control device 1 is equipped with a regenerating column 20 for an absorbing solution, a reflux flow rate regulating means for adjusting a reflux flow rate returned from a reflux drum 30 for the regenerating column for the absorbing solution to the regenerating column 20 for the absorbing solution, a reboiler calorie controlling means for adjusting a reboiler calorie of the regenerating column 20 for the absorbing solution, a means for detecting the circulating amount of the absorbing solution between the regenerating column 20 for the absorbing solution and gas cleaning columns 11 and 12 and a controlling means 2 for regulating the reflux flow rate controlling means and the reboiler calorie controlling means based on the absorbing solution circulating amount detected by the absorbing solution circulating amount detecting means.