A coding device includes a coding unit (740) for encoding an input digital signal using code words contained in one of a plurality of variable length code word groups, and a multiplexer (701) for generating a stream by generating a parameter (such as idr_pic_id) describing specific information about the stream, encoding the parameters, and adding it to the output data from the coding unit. The length of the code words contained in any single variable length code word group is the same. The multiplexer selects one variable length code word group containing three or more code words out of the plural groups, and codes the parameter using one code word selected from the code words contained in the selected group.