In ad hoc networks, unidirectional links between nodes exist due to differing propagation patterns or wireless interferences. Routing protocols for bidirectional links must cause the decline of connectivity. In recent years, some routing protocols considering unidirectional links have been proposed. However, these protocols have a problem: the broadcast traffic for backward path discovery increases. This paper proposes a novel routing protocol for ad hoc networks that positively uses unidirectional links and that drastically reduces the number of control packets. Our protocol improves network connectivity and reduces the number of control traffic.