A communication apparatus includes an arrival time estimation unit, connection selection unit, and network processing unit. The arrival time estimation unit estimates, for each block and each of a plurality of connections, an arrival time until a block generated by segmenting transmission data arrives from the apparatus at a final reception terminal or a merging apparatus through a network. The connection selection unit selects, for each block, a connection with the shortest arrival time from the plurality of connections on the basis of the estimation result. The network processing unit outputs each block to the network by using the selected connection. A data communication method and a data communication program are also disclosed.