The utility model relates to the field of cigarette detection in cigarette production industry, in particular to an infrared optical fiber type cigarette loose end detecting device, which comprises an infrared sensor, a photoelectric conversion circuit and a signal processing circuit. A signal input end of the infrared sensor is used for being connected with the end of a cigarette through an optical fiber, a signal output end of the infrared sensor is connected with a signal input end of the photoelectric conversion circuit, a signal output end of the photoelectric conversion circuit is connected with a signal input end of the signal processing circuit, and a signal output end of the signal processing circuit is used for being connected with a control computer. The infrared optical fiber type cigarette loose end detecting device is simple in structure, insusceptible to tobacco shred structure, moisture, environment temperature and environment humidity, and capable of correctly removing unqualified cigarettes and reserving qualified cigarettes, so that operating efficiency is improved, product quality is guaranteed, and tobacco shred waste is avoided.