An image forming device is provided which embeds a decodable two-dimensional code when embedding (printing) a two-dimensional code in an original document. The image forming device represents additional information by associating virtual points with dots in one-to-one correspondence and arranges dots in positions deviated from virtual points associated with the dots. The image forming device includes a determining unit for determining intervals between the virtual points and virtual points adjacent to the virtual points and determining sizes of the dots, and an arranging unit for arranging dots having the determined sizes to respective virtual points having the determined intervals. The determining unit may determine dots to have sizes other than sizes proportional to the determined intervals.