The multichannel data transfer apparatus is connected to a transmission line in which a plurality of connected nodes have their respective transmission channels and transmit compressed data in a predetermined present embodiment in accordance with bandwidths assigned to the respective channels, and the multichannel data transfer apparatus includes a calculating device that, when there is a request to change the number of transmission channels used to transmit compressed data in the transmission period, calculates a data compression rate and a transmission bandwidth for each of the transmission channels to be used in transmitting the compressed data to the transmission line when the number of the transmission channels is actually changed, and a notifying device that notifies each transmission channel of at least one of the calculated transmission bandwidth and transmission compression rate.