1. A digital watermark embedding device comprising: digital-watermark-pattern generating means which generates a digital watermark pattern based on embedding information; motion-detecting means which, based on the result of predetermined evaluation of motion vectors detected in units of blocks which are obtained by dividing a picture signal to be digitally watermarked, outputs a motion of the picture signal; modulating means which modulates the digital watermark pattern so as follow the motion; and embedding means which embeds the modulated digital watermark pattern in the picture signal.