A transport system includes a transport path 5, a line sensor unit 20, and a CPU. The transport path 5 transports bobbins 11 to and from an automatic winder that winds up a yarn to produce a package. The line sensor unit 20 includes a light source 22 and line sensors 23. The line sensors 23, which are arranged such that their detection direction is coincident with the axial direction of the bobbin 11, detect a bobbin being transported on the transport path 5. The CPU controls the line sensor unit 20.