To provide a coder that copes seamlessly with a change in the number of channels with respect to a digital broadcast employing coded multi-channel audio data.

The vocoder 10 that encodes supplied audio data of a plurality of channels is provided with a plurality of coders 14, 15, 16 that encode the audio data of a plurality of channels, a system controller 11 that receives information relating to the audio data of a plurality of the channels and selects a coder encoding the audio data out of a plurality of the coders, a stream generator 17 that integrates codes respectively outputted from a plurality of the coders into one code, and a code quantity controller 13 that receives the output of the system controller and sets the code quantity of each coder.