Camera installation flexibility on a moving object can be increased and accuracy in identifying the moving object improved by identifying a moving object origin trajectory as a potential position at which the moving object origin exists under the following conditions: 1) A distance between the moving object origin position and a reference virtual camera is constant. 2) A direction of virtual camera VCij as viewed from the moving object coordinate system (moving object origin Om) is constant (angle formed by two lines that direct to marker Pj and to the moving object origin position Cij as viewed from the virtual camera VCij is constant.) 3) Virtual camera VCij exists on marker circle (angle between markers Pi and Pj as viewed from virtual camera VCij is constant). It is possible to identify the position of moving object M by calculating the intersecting point of each moving object origin trajectory T upon multiple trajectories of moving object origin existing.