MONITORING SYSTEM, MONITORING METHOD, MONITORING DEVICE, AND FUNCTION RESTRICTING DEVICE

A monitoring system is for monitoring a vehicle (10) or a monitoring target that operates inside the vehicle (10), and the monitoring system includes: a reliability manager (1186) that manages reliability indicating a security protection state of the monitoring target, according to a vehicle event of the vehicle (10); and a function restrictor (1163) that places a restriction on at least a part of functions of the monitoring target, according to the reliability.