A watermarked content generating device including processing circuitry which performs active element conversion that converts a specified active modification target element from among elements included in an original content, based on a modification control code that is generated based on embedded information, when generating a structured content including at least a structured document, and performs passive element conversion that converts a specified passive modification target element from among elements included in the original content such that a change in a perceptual aspect of the original content corresponding to an active modification result element which results from the active element conversion is returned to having a same or equivalent perceptual aspect as that of the original content.