Before software for a routing protocol in a second wireless terminal receives a routing packet between a first wireless terminal and the second wireless terminal that are both included in an ad hoc network, stability determining software determines whether or not a link between the first wireless terminal, which is the source of the routing packet, and the second wireless terminal is stable. When the link is determined to be stable, the software for the routing protocol in the second wireless terminal processes the routing packet. This allows building of a route using only a stable link between adjacent nodes.