1. An image processing apparatus comprising: a storage which stores identification information for identifying a real object and three-dimensional image data of a virtual object associated with each other; a reader which reads three-dimensional image data of a virtual object associated with identification information on an image of a real object included in a frame image captured by an imaging apparatus from the storage; a display controller which displays the virtual object on a display in association with a displayed position of the real object using read three-dimensional image data; and a change detector which detects a temporal state change of images of the real object captured by the imaging apparatus, wherein the display controller superimposes the virtual object on the displayed position of the real object in such a manner that the real object is visible on the display and controls the virtual object as displayed based on the state change detected by the change detector, the change detector includes a movement quantity monitoring unit which monitors movement quantity of the real object captured by the imaging apparatus, and the display controller does not make the virtual object follow the real object in case the movement velocity of the real object is determined to exceed a predetermined reference velocity by the movement quantity monitoring unit.