To observe frequent occurrence of fluff in the spinning of a compact yarn without installing a single-purpose fluff-detecting device.

A spindle motor 11 for driving each spindle 10 is installed in each of the spindle 10. A ring rail 12 and a drafting device 13 are driven by a motor separate from the spindle motor 11. A fiber bundle-collecting device 17 is arranged at the downstream side of a pair of final delivering rollers of the drafting device 13. An electric current sensor for detecting a current intensity fed to the spindle motor 11 corresponding to the load acting on the spindle motor 11 installed in each spindle 10 is installed in each of the spindles. A judging means is also installed. The judging means judges the spindle to be in a state having much fluff, when the value detected by each electric current sensor is lowered to the one same to or less than that corresponding to a condition having much fluff, and larger than that corresponding to the load at yarn break.