As the performance of each node becomes higher, it is expected that the ad hoc network is used for the community network in which a few thousands of mobile nodes exist. In such a network, the number of hops between a source node and a destination node also becomes longer. However, as the route becomes longer, it is difficult to provide the robust and reliable route for mobile ad hoc networks since the multiple route breaks occur at the same time due to the topology change. Therefore, this paper proposes a Route-Split Routing resilient to simultaneous failure (RSR). RSR sets up multiple Subroute Management Nodes (SMN's) on the route and each SMN manages the subroute between the SMN and the neighboring SMN. When the multiple route breaks occur at the same time, each subroute is repaired by the SMN. Consequently, RSR can reduce the number of control packets used for the route repair and mitigate the network congestion even in case that the number of nodes in the network becomes very larger.