A spinning unit 1 includes a draft device 5, a spinning device 6, a tension stabilizing device 8, a winding device 9, and a yarn defect detecting device 7. The draft device 5 drafts a fiber bundle F. The spinning device 6 produce a spun yarn Y from the fiber bundle F drafted by the draft device 5. The tension stabilizing device 8 stabilizes tension of the spun yarn Y produced by the spinning device 6. The winding device 9 winds a package 91 of the spun yarn Y fed from the tension stabilizing device 8. The yarn defect detecting device 7 can detect a yarn defect in the spun yarn Y. The yarn defect detecting device 7 is arranged between the spinning device 6 and the tension stabilizing device 8.