PURPOSE: To detect collapse of a yarn package with a high productivity.

CONSTITUTION: A device for detecting collapse of winding of a yarn package comprises a motor as a yarn package rotating means for rotating a yarn package 1 about a spool as a rotating center, a sensor 4 as an optical distance measuring means for measuring a distance to an object in a noncontact manner, and a determining part 5 as a determining means for determining whether the winding collapses or not. The sensor 4 is located at a position opposing an end face of a yarn package 1 which is rotated by the motor 3. The end face of the package 1 is scanned by the sensor 4 while an actual distance between the sensor 4 and the end face of the package is measured. If the measured actual distance is deviated from a reference distance which exhibits no collapse of the winding, the determining part 5 counts the number of the occurrence times as the number of occurrence times of abnormality in distance. Then, if the number of occurrence times of abnormality exceeds the reference number of times, it is determined that collapse occurs in the yarn package 1.