The present invention makes improvements in a mobile communication system that performs a communication via a communication network provided in a mobile body to execute a data transfer. The present system comprises a plurality of nodes, a path control device which receives data from the nodes respectively, selects a path for the data transfer on the communication network, and outputs the data, first optical fibers which connect each of the nodes and the path control device and transfer the data, and second optical fibers provided in parallel with the first optical fibers. In the present system, the path control device communicates with the node via the second optical fiber when a failure occurs in the first optical fiber.