A document management site registers a scan document, generates a URL of the scan document and transmits it to an image forming apparatus (an image processing apparatus), the image forming apparatus posts the registered scan document on an SNS site by using the URL of the scan document. The document management site generates a comment ticket that is control information for causing the image forming apparatus to transmit a comment about the posted content shared in the SNS site, and the image forming apparatus acquires the comment ticket from the document management site. Then, the image forming apparatus transmits the comment about the posted content and information relating to an electronic document for a comment according to the comment ticket.