Disclosed are a packet transmission apparatus and so on that can suppress transmission delays caused by packet integrations and that can perform the transmissions over a broad band. The packet transmission apparatus includes: a packet extraction means that searches for and extracts, from a buffer for sorting and accumulating packets for respective destinations, the packets for the respective destinations and that, if a plurality of packets addressed to an identical destination have been accumulated in the buffer, extracts the plurality of packets from the buffer; and an encapsulation means that encapsulates the packets, which have been extracted by the packet extraction means, into a single packet for each destination.