To inform a control center in real time by taking the real time of an air conditioner controller with a monitoring device and detecting a gap of the time and a stop of the time generated by an interruption of service or a malfunction of the air conditioner controller itself with the monitoring device.

A controller time reading means 31 provided in the monitoring device 30 reads the controller time as the real time of the air conditioner controller, which is stored in a controller time memory means 23 provided in the air conditioner controller 20, in order. A gap between the read controller time and the system reference time as the reference time of the ice heat-storage type air conditioner monitoring system is computed, and when the gap is a certain value or more, abnormality of the controller time is informed.