A variable-length decoding (VLD) unit performs a variable-length decoding on an MPEG video stream. An inverse quantization (IQ) unit computes a discrete-cosine-transform (DCT) coefficient by performing an inverse quantization on results of decoding by the VLD unit. An inverse-discrete-cosine-transform (IDCT) unit carries out an IDCT for the DCT coefficients computed by the IQ unit so as to convert frequency components into the original signals. A motion-compensated-prediction (MC) unit performs a best-effort reproduction processing on received frames, during the time until the arrival of a frame serving as a reference for decoding, and returns to a normal decoding processing after the reference frame has been received.