To attain seamless switching that causes no failure on a coded signal in the case of switching a duplicate system and to enhance reliability.

An encoder 12 acting like an active system informs, in real time, an encoder 15 acting like a standby system about state parameter information denoting the state of the encoder 12 and processing MPEG coding format, and the encoder 15 matches the state of itself and the coding format with those of the encoder 12 on the basis of the informed state parameter information. Furthermore, synchronization sections 11, 14 synchronize a source signal between the systems before the encoders 12, 15 receive the source signal. An encoder output changeover device 13 selects respective outputs of the encoders 12, 15 and outputs the selected output.