To provide a yarn cleaning method and a yarn cleaning device by cutting-off a defect.

In this yarn cleaning method, at least one of a yarn parameter is measured by a measuring head 5, a defect which is not allowable is detected based on the yarn parameter, and the defect is cut off from the yarn 1. When a group of the defects is detected, cutting-off of the defects one by one is restrained promptly so that the plural defects are cut off all together at once. This yarn cleaning device contains the measuring head 5, a cutting-off and yarn joining device 7, and a control device 6. The control device 6 is constituted so that the method is performed.