A technique for distributing digital contents capable of effectively protecting copyrights and the like on the basis of invisible electronic watermark information and electronic watermark information is to be provided. On the sending side, additional information including copyright-related information is embedded into digital contents in advance as invisible electronic watermark information, while on the receiving side, additional information as the embedded invisible electronic watermark information is decoded and extracted as visible watermark information, the extracted information is embedded again into the digital contents, and the additional information is distributed or outputted as visible information together with the digital contents.