An apparatus and method for embedding additional information embeds plural pieces of additional information on a signal as electronic watermark information. In detail, plural pieces of additional information to be embedded on a signal are generated, the additional information is converted into electronic watermark information, the sizes of embedding parts for respective electronic watermark information are defined under control, and the electronic watermark information is embedded on the signal based on the control signal. Therefore, the additional information are embedded so that additional information having a higher significance degree can be more reliably and rapidly detected.