A leading vehicle group 1 transmits divided data 71 and 72 obtained by dividing vehicle information 7. Data transfer vehicle groups 2 and 3 transfer the divided data 71 and 72 to a data composite vehicle group 4 and to following vehicle groups 5 and 6. The data composite vehicle group 4 transfers composite data 73 obtained by XORing the divided data 71 and 72 to the following vehicle groups 5 and 6. The following vehicle group 5 XORs the divided data 71 received from the data transfer vehicle group 2 with the composite data 73 received from the data composite vehicle group 4 to restore the unreceived divided data 72.