There is provided a technique capable of easily and suitably setting or updating the setting information or the firmware of a plurality of network devices. According to a network device management method, a device information managing section transmits identification information and device information A of a network device, correlates identification information and device information B received from the other network device with the own identification information, generates approximation-level information, and stores this in an identification information database. A command receiving section that has received a setting/updating command C1 stores this setting/updating command in a command database. A setting/updating processing section carries out the setting or updating of the own network device. A command transfer section selectively transfers a setting/updating command to other network devices based on approximation-level information.