A storage unit stores a plurality of pieces of image information and a plurality of pieces of position information corresponding to respective ones of the plurality of images individually. The storage unit correlates the plurality of pieces of image information with respective ones of the plurality of pieces of position information individually. The plurality of images is displayed on the display based on the plurality of pieces of image information and the plurality of pieces of position information, respectively. An image selection unit selects at least a first image and a second image from the plurality of images. An information interchange unit interchanges first image information of the first image with second image information of the second image, or interchanges first position information of the first image with second position information of the second image. The storage unit stores and correlates the first image information and the second position information, and stores and correlates the second image information and the first position information. A display controlling unit controls the display to display one image based on the first image information and the second position information, and another image based on the second image information and the first position information.