The present invention provides an electronic watermark editor for a compressed video that can efficiently carry out editing such as deletion or rewriting of electronic watermark data.DCT coefficient values are extracted while applying all templates to video contents, and a template where a total sum of relative absolute value differences between pairs of the DCT coefficient values is maximized is judged to be an applied template. The pairs of DCT coefficient values extracted by the applied template are processed by a smoothing process section so that the relative differences are reduced and so as to reduce individual relative differences recursively until significant differences between the coefficient value pairs are statistically eliminated. In addition, the pairs of DCT coefficient values extracted by the applied template are replaced with new editing bits.