An image forming apparatus that assists classification of printed sheets of documents of print jobs includes: a correspondence table showing correspondence between sticky note attributes and keywords; and a hardware processor. The attributes represent appearance features of sticky notes to be attached to edges of the sheets so as to protrude from the edges. The keywords are extracted from the documents and denote topics of the documents. In response to execution request of a new print job, the hardware processor extracts a keyword from a document of the new job, judges whether the extracted keyword partially matches any keyword in the correspondence table, and when judging positively, creates a new sticky note attribute partially having an appearance feature represented by the sticky note attribute corresponding to the partially matching keyword in the correspondence table, and adds the new sticky note attribute to the correspondence table together with the extracted keyword.