The utility model relates to a cold rolling technical field, in particular to looping car belted steel off tracking detection device, include: detect grating, control box, infrared transmitting device, infrared receiving device and controller. The setting of measuring grating is on the looping car, and the measuring grating aligns with the central line of belted steel. The control box is connected with detection grating and battery, detects the grating and is sheltered from back output signal voltage to control box, infrared transmitting device and infrared receiving device set up relatively, infrared transmitting device is connected with the control box, to infrared transmitting device power -off processing behind the control box received signal voltage, infrared receiving device is connected with the controller, during the unable receipt infrared ray of infrared receiving device, reaches the controller in the producing signals change volume. The utility model provides a looping car belted steel off tracking detection device has realized the real -time supervision to looping car belted steel position, sends out the police dispatch newspaper when the belted steel off tracking, avoids the belted steel off tracking to cause serious production accident.