In a mixed-reality presentation system, a handler for manipulating a virtual object is displayed as a virtual object. Then, manipulation of the handler by the hand(s) of an observer is detected as manipulation of the virtual object associated with the handler, and those detection results are reflected in a display of the manipulated virtual object. By dynamically changing virtual objects displaying the handler according to the size of the virtual objects displayed in a view volume of the observer presented with a mixed reality space, the observer can select a desired virtual object with ease.