SOx removal equipment for reducing sulfur oxides from flue gas from a boiler, a cooler which is provided on a downstream side of the SOx removal equipment for reducing the sulfur oxides that remain in the flue gas and for decreasing a gas temperature, CO2 recovery equipment which includes a CO2 absorber, and an absorption liquid regenerator, and mist generation material reduction equipment for reducing a mist generation material which is a generation source of mist that is generated in the CO2 absorber of the CO2 recovery equipment before introducing the flue gas to the CO2 recovery equipment are included.