An instruction is detected which indicates that a physical object having a fixed plane where the physical object can be moved, and a virtual object rendered so as to be positioned on the plane where the physical object can be moved, are observed as being in a predetermined positional relationship. Then, a difference between a position and orientation value of the virtual object and a position and orientation value of the physical object is acquired at the time when the instruction is detected, so that the difference is used as a correction value to correct the positional difference between the physical object and the virtual object.