1. An apparatus for forming an externally framed image in which the externally framed image is formed by connecting, with an upper ruled line and a lower ruled line, an upper extension line and a lower extension line of a front decorative-figure image constituting a front end portion of an external frame to an upper extension line and a lower extension line of a rear decorative-figure image constituting a rear end portion of the external frame, respectively, said apparatus comprising a CPU configured to: dispose the front decorative-figure image, the rear decorative-figure image, the upper ruled line and the lower ruled line so that one outside contour of the upper ruled line coincides with an outside contour of the upper extension line of the front decorative-figure image and the other outside contour of the upper ruled line coincides with an outside contour of the upper extension line of the rear decorative-figure image, and one outside contour of the lower ruled line coincides with an outside contour of the lower extension line of the front decorative-figure image and the other outside contour of the lower ruled line coincides with an outside contour of the lower extension line of the rear decorative-figure image, set an image adjustment region inclusive of at least one of a connecting point between the upper extension line of the front decorative-figure image and the upper ruled line, a connecting point between the lower extension line of the front decorative-figure image and the lower ruled line, a connecting point between the upper extension line of the rear decorative-figure image and the upper ruled line, and a connecting point between the lower extension line of the rear decorative-figure image and the lower ruled line, and adjust an inside contour of the extension line or the ruled line in the image adjustment region so that the inside contour of the extension line coincides with the inside contour of the ruled line at the connecting point.