Detector for broken thread of sewing machine

The utility model provides a thread break detector used in a sewing machine, relating to a detector, which solves the problems existed in prior thread break detector of a sewing machine such as complex structure, high cost, narrow application scope as well as inconvenient positioning and debugging. The thread break detector used in a sewing machine comprises a positioning seat and a torsion spring arranged on the positioning seat, wherein one end of the torsion spring is provided with a feeler lever, which is provided with a hole for the sewing thread to through, an inductive chip is arranged on the positioning seat which is arranged to insulate with the torsion spring, the torsion spring and the inductive chip are connected with the two electrodes of a power supply by a conducting wire, an I/O unit receiving current signal is connected in series with the circuit between the torsion spring and the inductive chip, the controlling system which can detect the occurrence of thread break is connected with the I/O