Method and device for indicating thread breaks in a thread group, the beam of a laser being aligned with a rotating mirror and the thread group thereby being covered in constant repetition. Arranged transversely to the thread running direction is a multiplicity of detectors which have mutually overlapping recording ranges and of which the sum signals in the form of pulses are evaluated electronically. Faulty switching operations are avoided, even in the case of the lowest linear densities, as a result of the multiple scanning within a cycle.
