A transmitting side encapsulates extended transport packets, created by adding reproduction time information to each transport packet, and transmits them with capsule counter information added. The receiving side, having accumulation means, transmits a retransmission request, including the capsule counter information, to the transmitting side when a packet loss occurs. After receiving retransmitted data, the receiving side overwrites the received data in the primary storage area. The receiving side references the reproduction time information at reproduction time, compensates for jitters, andthen decodes the data. In this way, the transmitting side and the receiving side compensate for a packet loss or jitters over a communication network such as the Internet to prevent a decoding error on the receiving side.