A network-management device includes a map storing unit and a map state storing unit. The map storing unit stores therein a map created based on information on network devices. The map state storing unit stores therein a creation state indicating that creation of the map is in process or completed in association with the map. When creation of the map is in process, disclosure of the map is prohibited, and all the network devices are notified that creation of the map is in process. When creation of the map is completed, it is checked whether all the network devices are laid out on the map. When all the network devices are laid out on the map, disclosure of the map is permitted.