An air-conditioning control system comprising: outside air temperature input means for inputting outside air temperature information from a thermometer; characterized by outside air temperature coefficient calculation means for calculating, based on an outside air temperature calculated from the outside air temperature information input by the outside air temperature input means, a ratio of a current outside air temperature to a maximum outside air temperature during air-cooling, and a ratio of a temperature difference between a current outside air temperature and a predetermined room temperature to a temperature difference between a minimum outside air temperature and the room temperature during air-heating, as an outside air temperature coefficient; peak operating rate calculation means for calculating a peak operating rate, wherein the peak operating rate corresponds to a ratio between an actual quantity of electric power used by an air conditioner at the time of the maximum outside temperature during air-cooling or at the time of the minimum outside air temperature during air-heating, and a rated quantity of electric power used of the air conditioner; average operating rate calculation means for calculating an hourly average operating rate by multiplying the peak operating rate calculated by the peak operating rate calculation means by the outside air temperature coefficient calculated by the outside air temperature coefficient calculation means; average surplus rate calculation means for calculating an average surplus rate by subtracting the average operating rate calculated by the average operating rate calculation means from 1; control rate calculation means for calculating a control rate, wherein the control rate is equal to the average surplus rate calculated by the average surplus rate calculation means in case the average surplus rate is lower than a predetermined value and is equal to the predetermined value otherwise, wherein the predetermined value sets an upper limit for the control rate; and air-conditioning control means for performing energy-saving control of the air conditioner by stopping the air conditioner in a predetermined pattern in accordance with a quantity of the calculated control rate, or by performing an inverter-control of the rated quantity of electric power used by the air conditioner in accordance with a quantity of the calculated control rate. outside air temperature input means for inputting outside air temperature information from a thermometer; characterized by outside air temperature coefficient calculation means for calculating, based on an outside air temperature calculated from the outside air temperature information input by the outside air temperature input means, a ratio of a current outside air temperature to a maximum outside air temperature during air-cooling, and a ratio of a temperature difference between a current outside air temperature and a predetermined room temperature to a temperature difference between a minimum outside air temperature and the room temperature during air-heating, as an outside air temperature coefficient; peak operating rate calculation means for calculating a peak operating rate, wherein the peak operating rate corresponds to a ratio between an actual quantity of electric power used by an air conditioner at the time of the maximum outside temperature during air-cooling or at the time of the minimum outside air temperature during air-heating, and a rated quantity of electric power used of the air conditioner; average operating rate calculation means for calculating an hourly average operating rate by multiplying the peak operating rate calculated by the peak operating rate calculation means by the outside air temperature coefficient calculated by the outside air temperature coefficient calculation means; average surplus rate calculation means for calculating an average surplus rate by subtracting the average operating rate calculated by the average operating rate calculation means from 1; control rate calculation means for calculating a control rate, wherein the control rate is equal to the average surplus rate calculated by the average surplus rate calculation means in case the average surplus rate is lower than a predetermined value and is equal to the predetermined value otherwise, wherein the predetermined value sets an upper limit for the control rate; and air-conditioning control means for performing energy-saving control of the air conditioner by stopping the air conditioner in a predetermined pattern in accordance with a quantity of the calculated control rate, or by performing an inverter-control of the rated quantity of electric power used by the air conditioner in accordance with a quantity of the calculated control rate.