An air-conditioning system comprising: an outside air processing device configured to adjust a temperature of outside air taken into the outside air processing device and to supply the outside air to a plurality of indoor spaces; and an air-conditioning device including a plurality of indoor units at least one of which is installed in each of a plurality of target spaces (SP1, SP2) that are some or all of the indoor spaces, the air-conditioning device being configured to adjust temperatures of air in the target spaces (SP1, SP2), the air-conditioning system further comprising a control unit configured to adjust a flow rate of air blown into each target space (SP1, SP2) by the outside air processing device in accordance with an operating state of the at least one of the indoor units to reduce power consumption of the air-conditioning system characterized in that if a total airflow rate of the outside air processing device is to be increased, the control unit controls an increment of the flow rate of air blown into one of the target spaces (SP1, SP2) provided with the at least one associated indoor unit having a relatively high load factor to be greater than an increment of the flow rate of air blown into another one of the target spaces (SP1, SP2) provided with the at least one associated indoor unit having a relatively low load factor, where the load factor of the indoor unit represents a ratio of a load of the indoor unit to a rated capacity of the indoor unit, and the increment of the flow rate of air blown into each target space (SP1, SP2) represents an amount of increase in the flow rate of air blown into the target space (SP1, SP2) by the outside air processing device. an outside air processing device configured to adjust a temperature of outside air taken into the outside air processing device and to supply the outside air to a plurality of indoor spaces; and an air-conditioning device including a plurality of indoor units at least one of which is installed in each of a plurality of target spaces (SP1, SP2) that are some or all of the indoor spaces, the air-conditioning device being configured to adjust temperatures of air in the target spaces (SP1, SP2), the air-conditioning system further comprising a control unit configured to adjust a flow rate of air blown into each target space (SP1, SP2) by the outside air processing device in accordance with an operating state of the at least one of the indoor units to reduce power consumption of the air-conditioning system characterized in that if a total airflow rate of the outside air processing device is to be increased, the control unit controls an increment of the flow rate of air blown into one of the target spaces (SP1, SP2) provided with the at least one associated indoor unit having a relatively high load factor to be greater than an increment of the flow rate of air blown into another one of the target spaces (SP1, SP2) provided with the at least one associated indoor unit having a relatively low load factor, where the load factor of the indoor unit represents a ratio of a load of the indoor unit to a rated capacity of the indoor unit, and the increment of the flow rate of air blown into each target space (SP1, SP2) represents an amount of increase in the flow rate of air blown into the target space (SP1, SP2) by the outside air processing device.