An object of the present invention is to provide an electronic watermark embedding apparatus, an electronic watermark embedding method, a record medium having an electronic watermark capable of securely detecting the watermark in the case of performing the noise reduction process or data compression process to the information on the contents and a manufacturing method of record medium. The electronic watermark embedding apparatus is provided with an embedding device for embedding an electronic watermark comprised of a signal generated based on a predetermined rule into contents comprised of digital information; a variation device for varying intensity of the electronic watermark to be embedded into the contents; and a controlling device for controlling the variation device so as to change the intensity of the electronic watermark, and wherein the controlling device for controlling the variation means so as to increase the intensity of the electronic watermark at intervals are provided.