PROBLEM TO BE SOLVED: To provide a time stamp device by which data information difficult in deletion and revision is added to digital contents without impairing image quality. SOLUTION: Image pickup date information set by a data information setting section 3 is converted into an image signal by an image pickup section 1, the image signal is embeded into a digital image signal of an objet image converted by an A/D converter section 2 at a watermark embeding section 4 by the digital watermark technology so as to add the data information whose deletion and revision are difficult to the object image without impaing image quality. Furthermore, in the case of extracting the impairing pickup date information sets of two kinds or over when the embedded information is extracted from the image signal, it is discriminated that the data information is a synthesis image by illegal use.