An ad hoc wireless network supports data networking without an infrastructure, so that users can use network services while continually moving. Each move of the mobile host affects the topology of the network and the transmission route. The Ad Hoc Backup Node Setup Routing Protocol (ABRP) is proposed to focus attention on the intrinsic properties of the ad hoc wireless networks. Basically, ABRP chooses some routes as backup routes from a number of routes between the source and destination. It more completely considers the quality of routing than the routing protocols proposed in the past. ABRP involves three phases: route discovery, backup node setup and route maintenance. In the route discovery phase, a node is allowed to receive duplicate requests for finding many routes to reach a destination. In the backup node setup phase, those routes, almost more than one, can be analyzed to obtain some good backup routes and can be saved in the backup route cache of the backup nodes. In the route maintenance phase when situations involving disconnection or loss of connection, these backup routes can be found rapidly. Furthermore, ABRP provides a backup route mechanism that reconnects quickly as required for ad hoc wireless networks.