1. A management system, comprising an interface coupled to a network, a processor coupled to the interface, and a storage device coupled to the processor, wherein the interface has coupled thereto at least one maintenance target machine to be a target of a maintenance operation, which is identified by one piece of identification information, and wherein the management system is configured to: store information indicating a scheduled start time and scheduled finish time of the maintenance operation; determine, based on the scheduled start time, the scheduled finish time, and a login and logout for the maintenance operation on the at least one maintenance target machine detected by the management system, whether or not the maintenance operation is in execution on the at least one maintenance target machine; and determine, based on a result of the determination, whether or not to execute predetermined processing associated with an event transmitted from the at least one maintenance target machine.