An air-conditioning system control apparatus configured to control an air-conditioning system, the air-conditioning system comprising: a ventilation apparatus including a carbon dioxide concentration detection sensor, and configured to ventilate air in an air-conditioning target space based on a set ventilation air volume corresponding to a necessary ventilation air volume; and an air-conditioning apparatus configured to take in the air in the air-conditioning target space and supply the intake air to the air-conditioning target space, the air-conditioning system control apparatus comprising: a storage device configured to store data to be used for control of the ventilation apparatus and control of the air-conditioning apparatus; a computing device configured to generate a control command for controlling the ventilation apparatus and a control command for the air-conditioning apparatus based on the data stored in the storage device, the computing device including a ventilation air volume correction coefficient generation part configured to generate a ventilation air volume correction coefficient for correcting the set ventilation air volume based on an operation condition of the ventilation apparatus, an operation condition of the air-conditioning apparatus, operation data of the ventilation apparatus stored in the storage device, and operation data of the air-conditioning apparatus stored in the storage device, an operation state determination unit configured to calculate the set ventilation air volume based on temporal fluctuation data of a carbon dioxide concentration and correct the set ventilation air volume with the ventilation air volume correction coefficient, and a control command generation unit configured to generate the control command for controlling the ventilation apparatus and the air-conditioning apparatus based on the set ventilation air volume corrected by the operation state determination unit. a ventilation apparatus including a carbon dioxide concentration detection sensor, and configured to ventilate air in an air-conditioning target space based on a set ventilation air volume corresponding to a necessary ventilation air volume; and an air-conditioning apparatus configured to take in the air in the air-conditioning target space and supply the intake air to the air-conditioning target space, the air-conditioning system control apparatus comprising: a storage device configured to store data to be used for control of the ventilation apparatus and control of the air-conditioning apparatus; a computing device configured to generate a control command for controlling the ventilation apparatus and a control command for the air-conditioning apparatus based on the data stored in the storage device, the computing device including a ventilation air volume correction coefficient generation part configured to generate a ventilation air volume correction coefficient for correcting the set ventilation air volume based on an operation condition of the ventilation apparatus, an operation condition of the air-conditioning apparatus, operation data of the ventilation apparatus stored in the storage device, and operation data of the air-conditioning apparatus stored in the storage device, an operation state determination unit configured to calculate the set ventilation air volume based on temporal fluctuation data of a carbon dioxide concentration and correct the set ventilation air volume with the ventilation air volume correction coefficient, and a control command generation unit configured to generate the control command for controlling the ventilation apparatus and the air-conditioning apparatus based on the set ventilation air volume corrected by the operation state determination unit. a storage device configured to store data to be used for control of the ventilation apparatus and control of the air-conditioning apparatus; a computing device configured to generate a control command for controlling the ventilation apparatus and a control command for the air-conditioning apparatus based on the data stored in the storage device, the computing device including a ventilation air volume correction coefficient generation part configured to generate a ventilation air volume correction coefficient for correcting the set ventilation air volume based on an operation condition of the ventilation apparatus, an operation condition of the air-conditioning apparatus, operation data of the ventilation apparatus stored in the storage device, and operation data of the air-conditioning apparatus stored in the storage device, an operation state determination unit configured to calculate the set ventilation air volume based on temporal fluctuation data of a carbon dioxide concentration and correct the set ventilation air volume with the ventilation air volume correction coefficient, and a control command generation unit configured to generate the control command for controlling the ventilation apparatus and the air-conditioning apparatus based on the set ventilation air volume corrected by the operation state determination unit.