A monitoring system includes at least one sensor, at least one monitoring camera, a power control apparatus, a master device that is connected to a fixed telephone network so as to perform calls to other fixed telephones, and a mobile phone terminal that is connected to other mobile phones via a mobile phone network. A master device instructs the power control apparatus to supply power depending on whether or not an event is detected by at least two of the sensors and the monitoring cameras, and the power control apparatus supplies power to the connected apparatus on the basis of a power supply instruction from the master device.