PURPOSE: To protect a transformer and limitation of a working power through the control of the feed of power as well as that air conditioning of a plurality of rooms is performed by a method wherein an air conditioning load is individually detected by the temperature measuring means of each air conditioning device, and the air conditioning devices are operated, based on priority level, from the air conditioning device having a high air conditioning load.

CONSTITUTION: From the values of temperature measuring means 12aW12n, an air conditioning load necessary to each of air conditioning devices 1aW1n is determined by a computing means 7. The priority order of operation is determined so that the more a necessary air conditioning load is increased, i.e. the more a temperature difference between a measured temperature and a set temperature is increased, the more the priority level of operation is heightened. From a rated capacity of a transformer 2 stored in a memory part 8 and the value of a necessary power of each of the air-conditioning devices 1aW1n, the number of simultaneous operating devices is determined, and an operation/ stop signal is outputted to operation control parts 13aW13n of the air conditioning devices 1aW1n from an output control means 9.