To prevent deterioration of quality of a package 7 in a yarn winder.

The yarn winder is provided with a cradle 8 for supporting winding bobbins 6 and 7, a package driving motor 41 connected to the winding bobbins 6 and 7, and a contact roller 9 brought in contact with the peripheral surfaces of the winding bobbins 6 and 7 for driven rotation. A cradle driving mechanism 24 can move the cradle 8 between a lift-down position, in which the peripheral surfaces of the winding bobbins 6 and 7 are brought in contact with the contact roller 9, and a lift-up position, in which the peripheral surfaces of the winding bobbins are separated from the contact roller 9. In a lift-up, the contact roller 9 is braked by a brake mechanism 27. In the case wherein stop of the contact roller is imperfect due to abnormal condition of the brake mechanism 27, the package rotation sensor 43 indirectly detects inertia rotation of the contact roller 9 in a lift-down, and an alarm output means 52 lights up an alarm lamp 61 by outputting an alarm signal.

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