An inter-vehicle network that connects monitoring and control devices communicating with an intra-vehicle network that couples in-vehicle devices with the monitoring and control devices. A train clock station at an uppermost level in a hierarchical structure and a vehicle clock station in a middle level in a hierarchical structure are established from the monitoring and control devices. Other devices are established as a correction information waiting station at a lowermost level in the hierarchical structure. The train clock station performs a time correction of its own station with time information that is arbitrarily obtained as reference time. The vehicle clock station performs a time correction of its own station based on a message transmitted from the train clock station. The correction information waiting station performs a time correction of its own station based on a message transmitted from the vehicle clock station.