A CO2 recovery system includes an absorption tower that removes CO2 from exhaust gas, a regeneration tower that regenerates a rich solution, and a separation drum that condensates steam in CO2 gas released from the regeneration tower and separates water. The CO2 recovery system further includes a filtration membrane apparatus that filters solid content remaining in the lean solution using a filter, and cleans the filter using condensed water as cleaning water and again return the condensed water into the system. The CO2-absorbing solution attached to the filter is collected and the filter is cleaned without diluting the CO2-absorbing solution upon replacement of the filter.