1. An image displaying system for displaying image, comprising: an image storing unit storing thereon the image; a displaying unit operable to display the image, said displaying unit being carried by a user; a photographing unit operable to photograph exterior as a plurality of photographed images, said photographing unit being carried with said displaying unit all together; a travel distance computing unit operable to compute a travel distance of said displaying unit by analyzing the plurality of photographed images which are photographed by said photographing unit at different times; and a display control unit operable to change the image, which is different from photographed images, based on the travel distance computed by said travel distance computing unit and to causes said displaying unit to display the image, wherein said image storing unit associates change information for changing the image with the travel distance of said displaying unit; said display control unit causes said displaying unit to display the changed image based on the change information on the image associated with the travel distance computed by said distance computing unit referring to said image storing unit said image storing unit stores an original image, of which the area is larger than that of each of the images photographable by the photographing unit, and further stores a position in the original image as the change information, and said display control unit identifies the position in the original image based on change of direction of said displaying unit by referring to said image storing unit, trims the image from the original image so that the trimmed image is displayed on said displaying unit, and causes said displaying unit to display the image; wherein said travel distance computing unit detects a mode of movement of said displaying unit, the mode including a translational mode and a rotational mode, and said travel distance computing unit computes a travel distance corresponding to the detected mode of movement, wherein said travel distance computing unit detects distance to each of a plurality of subjects included in the photographed images, and detects the mode of movement of said displaying unit using the detected distance and the travel distance.