1. An image forming apparatus comprising: a scanning unit configured to read a first image, generate first image data representing the first image, read a second image, and generate second image data representing the second image; an image data synthesizing unit configured to generate, on the basis of the first and second image data, synthesized image data representing a synthesized image of the first and second images arranged in a contact state where a first side which is one of four sides constituting an outer edge of the first image and a second side which is one of four sides constituting an outer edge of the second image are disposed immediately adjacent to each other or in a close state in which these sides are disposed parallel to and close to each other; and a printing unit configured to print, on a recording medium, the synthesized image represented by the synthesized image data.