A wireless multi-hop communication system comprising: a plurality of wireless devices including a wireless repeater; a gateway configured to transmit and receive information with respect to each of the wireless devices; and a network management device configured to manage the wireless multi-hop network including the wireless devices including said wireless repeater and the gateway, the network management device including: a network configuration management unit configured to manage communication quality information, said communication quality information indicating measured communication quality between pairs of wireless devices and between a respective wireless device and the gateway; a repeater necessity determination unit configured to determine whether or not to add a repeater for each of the wireless devices based on the communication quality information, and to select a wireless device for which it is required to add a repeater based on a determination result; an access point determination unit configured to determine access points for the selected wireless device for securing a predetermined communication quality for the selected wireless device, the selection being made based on the communication quality information or positional information of the wireless devices and the gateway and configured to select an access point from the wireless devices or the gateway based on the determination result; and a repeater placement determination unit configured to determine whether there is a repeater installation location indicating an installation range of the repeater for relaying between the selected wireless device and the selected access point based on whether there is an overlap in the communication ranges of the selected wireless device and of the selected access point, wherein the repeater placement determination unit is configured to determine, when there is an overlapping portion indicating an area in which the communication ranges of the selected wireless device and of the selected access point overlap with each other, that the repeater placement location is at the overlapping portion, and to output the overlapping portion as the repeater installation location. a network configuration management unit configured to manage communication quality information, said communication quality information indicating measured communication quality between pairs of wireless devices and between a respective wireless device and the gateway; a repeater necessity determination unit configured to determine whether or not to add a repeater for each of the wireless devices based on the communication quality information, and to select a wireless device for which it is required to add a repeater based on a determination result; an access point determination unit configured to determine access points for the selected wireless device for securing a predetermined communication quality for the selected wireless device, the selection being made based on the communication quality information or positional information of the wireless devices and the gateway and configured to select an access point from the wireless devices or the gateway based on the determination result; and a repeater placement determination unit configured to determine whether there is a repeater installation location indicating an installation range of the repeater for relaying between the selected wireless device and the selected access point based on whether there is an overlap in the communication ranges of the selected wireless device and of the selected access point, wherein the repeater placement determination unit is configured to determine, when there is an overlapping portion indicating an area in which the communication ranges of the selected wireless device and of the selected access point overlap with each other, that the repeater placement location is at the overlapping portion, and to output the overlapping portion as the repeater installation location.