A range having a predetermined width close to a display margin is defined in an image as a restriction area. When the display area enters the restriction area, the moving speed determination unit reduces the speed of moving the display area in accordance with the extent that the display area enters the restriction area. When the request for moving the display area is suspended while the display area enters the restriction area, the bouncing speed determination unit determines the moving speed so that the display area is bounced in a direction away from the restriction area at a speed determined by the extent that the display area enters the restriction area. A frame coordinate computation unit computes frame coordinates of a display area that should be newly displayed, based on the moving speed determined by the moving speed determination unit and the bouncing speed determination unit.