This invention has as its object to provide a technique that can verify whether or not document data has been tampered with, by embedding identification information in document data in the background of the document data. To this end, this invention provides an information processing method for embedding additional information in document data, comprising a step of inputting document data, an extraction step of extracting identification information from the input document data as additional information, a step of inputting a predetermined image, an embedding step of embedding the additional information extracted in the extraction step in the input image, and a composition step of compositing the embedded image as a background image of the document data.