THREAD BREAKAGE DETECTOR FOR SEWING MACHINE

PROBLEM TO BE SOLVED: To provide a thread breakage detector for a sewing machine having improved thread breakage detection accuracy of a photosensor by effectively utilizing vibrations generated on a thread in a thread supply side and low in cost by simplifying the structure. SOLUTION: A thread 9 fed out of the thread supply source in sewing is normally vibrated with the amplitude of a certain degree between a supply source side thread guide and a thread breakage detector S, both guide holes 27 and 28 of the thread breakage detector S are largely opened to allow the thread 9 to vibrate, and both the guide holes 27 and 28 are located along the thread supply route. Therefore, the vibrations are easily propagated between both the guide holes 27 and 28 as well and the vibrations of that thread 9 can satisfactorily be detected by a photosensor 29.