A showcase control system comprising: showcase operating rate detection means for detecting an operating rate in showcase control means for controlling freezing or refrigerating inside a showcase; over-operating detection means for outputting an over-operating signal when the showcase operating rate input from the showcase operating rate detection means exceeds a predetermined value; and an air-conditioning control system for curtailing energy-saving control of an air conditioner when receiving an over-operating signal from the over-operating detection means, wherein the air-conditioning control system comprises outside air temperature input means to which outside air temperature information is input, 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 an outside air temperature at a maximum temperature in 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 an outside air temperature at a minimum temperature and the room temperature in air-heating, as an outside air temperature coefficient, peak operating rate calculation means for calculating an average operating rate of an air conditioner at the maximum temperature in air-cooling, and an average operating rate of the air conditioner at the minimum temperature in air-heating, as a peak operating rate, 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 (1 - average operating rate) as an average surplus rate with respect to the average operating rate calculated by the average operating rate calculation means, control rate calculation means for calculating a control rate whose maximum value is a predetermined value for the average surplus rate calculated by the average surplus rate calculation means, air-conditioning control means for performing energy-saving control of the air conditioner by a quantity of the control rate calculated by the control rate calculation means, case control rate calculation means for calculating a case control rate for performing energy-saving control of the showcase, and case control means for performing energy-saving control of the showcase by a quantity of the control rate calculated by the case control rate calculation means. showcase operating rate detection means for detecting an operating rate in showcase control means for controlling freezing or refrigerating inside a showcase; over-operating detection means for outputting an over-operating signal when the showcase operating rate input from the showcase operating rate detection means exceeds a predetermined value; and an air-conditioning control system for curtailing energy-saving control of an air conditioner when receiving an over-operating signal from the over-operating detection means, wherein the air-conditioning control system comprises outside air temperature input means to which outside air temperature information is input, 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 an outside air temperature at a maximum temperature in 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 an outside air temperature at a minimum temperature and the room temperature in air-heating, as an outside air temperature coefficient, peak operating rate calculation means for calculating an average operating rate of an air conditioner at the maximum temperature in air-cooling, and an average operating rate of the air conditioner at the minimum temperature in air-heating, as a peak operating rate, 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 (1 - average operating rate) as an average surplus rate with respect to the average operating rate calculated by the average operating rate calculation means, control rate calculation means for calculating a control rate whose maximum value is a predetermined value for the average surplus rate calculated by the average surplus rate calculation means, air-conditioning control means for performing energy-saving control of the air conditioner by a quantity of the control rate calculated by the control rate calculation means, case control rate calculation means for calculating a case control rate for performing energy-saving control of the showcase, and case control means for performing energy-saving control of the showcase by a quantity of the control rate calculated by the case control rate calculation means.