In a display screen of an image display device, plural menu items in a higher rank menu hierarchy are displayed in a first circular arrangement, and plural menu items in a lower rank menu hierarchy that is subsidiary to the higher rank menu hierarchy is displayed in a second circular arrangement that concentrically surrounds the first circular arrangement with a greater diameter than the first circular arrangement. In addition, a pointed-out portion in the display screen is identified according to a user operation to an operation device, and a function of a menu item in the lower rank menu hierarchy being in association with the identified pointed-out portion is realized by a processing for the function. Each of the menu items in the lower rank menu hierarchy is arranged in a position in a manner that expresses the subordination of the lower rank menu item to one of the menu items in the higher rank menu hierarchy.