To give flexibility to the advance order of moving members by allowing the moving member to circulate on a sub rail track without preventing movement of the moving member on a main rail track.

The transfer system has a track structure comprising a main rail track 20 and a sub rail track 22, on which a self-advancing trucks 21 travel. At the position where the main rail track 20 and the sub rail track 22 adjoin to each other, a shifter 23 is provided so as to be movable in the upward and downward direction of the drawing. The shifter 23 has a track switching rail 24 and a track switching rail 25. When the self-advancing truck 21 is moved from the main rail track 20 to the sub rail track 22, the track switching rail 24 moves to the sub rail track 22 with the self-advancing truck 21 mounted thereon, to thereby move the self-advancing truck 21.