A node device includes a transmitter, processor, and a receiver. The receiver receives a packet from an adjacent node device. The processor generates a cluster list and a first hello packet. The cluster list records device identification information of a node device included in a cluster. The cluster is a group of node devices for which route information is stored. The first hello packet reports the route information with cluster identification information of the cluster. The transmitter broadcasts the first hello packet. Upon receipt of, from a free-node device that does not belong to a cluster, a second hello packet that includes information that associates the cluster identification information with device identification information of the free-node device, the processor adds the device identification information of the free-node device to the cluster list until a number of node devices recorded in the cluster list reaches a threshold.