A communication system according to the present disclosure includes: a required band calculation unit (12, 41) configured to calculate a required band for a plurality of flows received by a bridge apparatus (3), in which, for a flow including burst data among the plurality of flows, the required band calculation unit (12, 41) calculates the required band for the flow based on a data size of the burst data and an allowable delay of the flow; and a speed ratio calculation unit (32, 43) configured to calculate a relative ratio of communication speeds of the plurality of flows based on the required band for the plurality of flows. The bridge apparatus (3) transfers the plurality of flows to a data receiving apparatus (2) according to the relative ratio of the communication speeds.