A multilane transmission device that transmits data frames by using a plurality of lanes, comprising: a data frame allocating unit that allocates data frames based on a transmission destination; a flow group information sequence information adding unit that adds flow group information indicating a flow group corresponding to a transmission source and transmission destinations and sequence information indicating a sequence of the data frames to the data frames allocated based on each transmission destination by the data frame allocating unit; and a lane selecting/outputting unit that transmits the data frames having the respective flow group information and the respective sequence information added thereto by the flow group information sequence information adding unit to the transmission destinations by using one or more lanes corresponding to the respective flow group information.