PURPOSE: To automate the control in accordance with a preset program by a central monitoring system by providing the central monitoring system with a timer circuit and a data indicator and controlling respective terminal control devices and air conditioners through a central control circuit based on the control signal from the timer circuit.

CONSTITUTION: Where performing a control with a timer circuit 49, the time, day, air conditioner numbers and operating hours for operating an air conditioner 3 are set by switches 7W10 on the main unit 1. That is, the timer is readied by pressing switches 8 and 9, and only those days of week in which the timer operation is wanted are indicated by illuminating lamps 6 on the main unit 1 with the ON and OFF designated by switches 8W11. Then, the operation starting time is displayed on an indicator 5 and set by the switches 8W11, and, upon completing its setting, the length of operation hours of air conditions is displayed on the indicator 5 and is set by the switches 8W11. To conclude the setting, the unit numbers for which the timer operation is wanted are illuminated by an operation command and monitoring lamp 11, and the unit numbers are set by a switch 12. After the setting is completed, a lamp 13 will come on when a switch 14 is pressed, and the timer operation starts.