PROBLEM TO BE SOLVED: To increase bandwidth without increasing latency.SOLUTION: A multi-lane transmission system performs a delay compensation when increasing lane number in a multi-lane transmission in which a frame format signal is divided into data blocks and the data blocks are distributed into a plurality of lanes to transmit. A duplication of data block including a synchronization pattern and a frame number of the existing lane are transmitted by a new lane in advance so as to compare delay of the synchronization pattern with respect to the same frame number. When delay of the synchronization pattern in the existing lane is larger than that of the new lane, the delay of difference is provided to the new lane. When the delay of the synchronization pattern in the new lane is larger than that of the existing lane, the delay of difference is provided to the existing lane to compensate the delay difference between the existing lane and the new lane, and then change the lane number for distributing the data block in the transmission side of the multi-lane transmission system.