The device for detecting a thread, comprises at least a first tight emitter (3)and at least a first tight receiver (5), disposed so that the tight beam (F1) emittedy the emitter and received by the receiver intersects the path (P) of the thread (F). The light beam received by the first receiver produces a first signal containing information on the thread. Also provided is at least a processing circuit (9) of said signal produced by the receiver, which extracts information from the signal on the presence and/or movement of the thread on the basis of the fluctuations of said signal caused by the irregular structure of said thread. |