To eliminate the necessity of machining the components and guide rails by achieving the enhanced positioning accuracy of a positioning system by using the minimum number of components.

A parallel moving device 10 for moving a cartridge inserting/ ejecting device 12 along a path 14 is provided with a first thin and long gear rack 20 positioned along the path 14, and a second thin and long gear rack 22 disposed away from the first thin and long gear rack 20 and positioned along the path 14. A first driving pinion 42 attached to the cartridge inserting/ ejecting device 12 engages with the first thin and long gear rack 20 and, similarly, a second driving pinion 28 engages with the second thin and long gear rack 22. A driving device 32 operated in relation to the first and second driving pinions 42 and 28 rotates the first and second driving pinions 42 and 28, and moves the cartridge inserting/ejecting device 12 along the first and second thin and long gear racks 20 and 22.