To efficiently allocate a plurality of carriers to target conveying operation points and to improve the conveyance capability by providing a looped subordinate conveyance track which is different from a main conveyance track and at least ≥2 connecting conveyance tracks which connects the main conveyance track and subordinate conveyance track together.

A control part 17 instructs for the allocation of carries 11a and 11b and controls tracks where the carriers 11a and 11b move. The carriers 11a and 11b have radio terminals respectively, receive the allocation indication sent by the control part 17 in the form of, for example, a radio signal, and move on the main conveyance track 14, subordinate conveyance track 15, or connecting conveyance track 16 according to the indication. Further, switching between the main conveyance track 14 and connecting track 16 where the carriers 11a and 11b travel and switching between the connecting track 16 and subordinate track 15 are performed according to the indication of the control part 17. When the control part 17 generates the allocation indication, the free carrier 11b moves to the main conveyance track 14 through the connecting conveyance track 16 to move to a target conveying operation point 13.