Position and orientation information of a specific part of an observer is acquired (S403). It is determined whether or not a region of a specific part virtual object that simulates the specific part and that of another virtual object overlap each other on an image of a virtual space after the specific part virtual object is laid out based on the position and orientation information on the virtual space on which one or more virtual objects are laid out (S405). When it is determined that the regions overlap each other, an image of the virtual space on which the other virtual object and the specific part virtual object are laid out is generated; when it is determined that the regions do not overlap each other, an image of the virtual space on which only the other virtual object is laid out is generated (S409).