There is disclosed an image synthesizing device that is provided with a
mode switching device for switching over between an overlay mode and an
inlay mode. In the overlay mode, image data of a subject image is input
into a memory in a size corresponding to a designated print size of a
composite image, and at least an additional image is overlaid on a
predetermined portion of the subject image. So the composite image having
a simple structure will be produced promptly in the overlay mode without
the need for complicated operations. In the inlay mode, a mount area is
defined in the memory in correspondence with a designated print size of a
composite image, and the subject image and at least an additional image
are inlaid in those ranges which are defined in variable sizes at
appropriate locations within the mount area.