Abstract: A monitoring system comprises a monitoring device, a terminal device that has an imaging function and transmits identification information, and the monitoring center. The monitoring device performs an authentication process of the terminal device based on the identification information received, and transmits first information that associates an authentication time, region information for specifying a monitoring region, and the identification information received. The terminal device transmits second information that associates an image in the monitoring region captured, a capture time of the image, and the identification information.