In the case where detection is made that a transmission button 13f displayed on an upload control screen 13a acquired from a web server is operated via a browser 21a having a function of uploading a file onto a web server 2, if a file name display field 13g is blank, a scanner 12 is instructed to start scanning an image of a document via operation of a scanning start button 16 for instructing to start scanning the image of the document. Then, image data output by the scanner 12 is digitized by a data digitization block 15f, and the digitized data is uploaded onto the web server 2. This enhances user convenience for uploading a file onto a web server using a browser having an upload function.