PROBLEM TO BE SOLVED: To provide a monitoring system allowing a monitor to quickly acquire that something abnormal occurs to a body of a monitoring object person, while reducing a processing load of a server device, and an activity meter for use in the monitoring system.SOLUTION: A monitoring system 1 comprises a server device 8, an activity meter 2 carried by a monitoring object person, and a receiver device 4 communicable with the server device 8 and the activity meter 2. The activity meter 2 includes an acceleration sensor 20 for generating activity data representing the activity of the monitoring object person； a control part 30； and a communication part 14 for transmitting the activity data to the receiver device. When the activity meter 2 is located within the communication object region, the receiver device 4 acquires the activity data from the activity meter 2 and transmits them along with an identifier to the server device. The server device 8 includes a communication part 63 for receiving the activity data and the identifier； an alarm determination part 69 for determining whether or not executing an alarm notification on the basis of the activity data and the identifier； and a control part 61 causing a management terminal device 100 to execute the alarm notification.
