A communication device used for a communication system performing monitoring of status of an Ethernet-based network by transmitting and receiving monitoring frames between each pair of maintenance entity group end point, MEP devices every predetermined time, the communication device constituting one of the MEP devices comprising: a receiving means for receiving the monitoring frames; a management table for managing identification information of the PEER MEP devices that are transmission sources of the monitoring frames; and an Ethernet Operation Administration and Maintenance, OAM processing part comprising: a registering means for, in a case that identification information of a PEER MEP device that is a transmission source of a monitoring frame received by the receiving means is not registered in the management table, registering the identification information of the PEER MEP device into the management table; a timing means for, regarding each of the identification information of the PEER MEP devices registered in the management table, measuring an elapsed time after reception of a monitoring frame from the PEER MEP device identified by the identification information by the receiving means; and a deleting means for, regarding at least any of the identification information of the PEER MEP devices registered in the management table, when a monitoring frame from the PEER MEP device identified by the identification information is not received even though the elapsed time measured by the timing means becomes equal to or more than a predetermined deletion threshold, deleting the identification information of the PEER MEP device from the management table. a receiving means for receiving the monitoring frames; a management table for managing identification information of the PEER MEP devices that are transmission sources of the monitoring frames; and an Ethernet Operation Administration and Maintenance, OAM processing part comprising: a registering means for, in a case that identification information of a PEER MEP device that is a transmission source of a monitoring frame received by the receiving means is not registered in the management table, registering the identification information of the PEER MEP device into the management table; a timing means for, regarding each of the identification information of the PEER MEP devices registered in the management table, measuring an elapsed time after reception of a monitoring frame from the PEER MEP device identified by the identification information by the receiving means; and a deleting means for, regarding at least any of the identification information of the PEER MEP devices registered in the management table, when a monitoring frame from the PEER MEP device identified by the identification information is not received even though the elapsed time measured by the timing means becomes equal to or more than a predetermined deletion threshold, deleting the identification information of the PEER MEP device from the management table. a registering means for, in a case that identification information of a PEER MEP device that is a transmission source of a monitoring frame received by the receiving means is not registered in the management table, registering the identification information of the PEER MEP device into the management table; a timing means for, regarding each of the identification information of the PEER MEP devices registered in the management table, measuring an elapsed time after reception of a monitoring frame from the PEER MEP device identified by the identification information by the receiving means; and a deleting means for, regarding at least any of the identification information of the PEER MEP devices registered in the management table, when a monitoring frame from the PEER MEP device identified by the identification information is not received even though the elapsed time measured by the timing means becomes equal to or more than a predetermined deletion threshold, deleting the identification information of the PEER MEP device from the management table.