A data transfer device, including a packet receiving unit to receive packets in a block including a data packet and an error-correction packet; a packet-loss detection unit to detect a packet loss from a head of a block received by the packet receiving unit of a received packet; a packet transfer unit to transfer the packet received from the packet receiving unit with a delay of a predetermined time; and a retransmission-request transmission unit to transmit a retransmission request to a packet-transmission source device based on the packet loss detected by the packet-loss detection unit and a determined retransmission time to retransmit the packet.