Wireless mesh network can increase service coverage by low-cost multiple-paths between a source and a destination. But because of the wireless nature, wireless mesh network is vulnerable to diversified threats. Especially attacks by malicious nodes can decrease the performance or ravage the network. Many protocols, based on Public Key Infrastructure (PKI), have been proposed to ensure security however; these protocols cannot efficiently prevent the cases of compromised nodes. In this paper, we propose a mesh router authentication scheme to solve this problem of existing protocols. Although our scheme increases the end-to-end delay, the proposed mesh router authentication scheme can guarantee secure wireless mesh network communication from malicious nodes.