Recently, an endoscopic approach has been preferred for a thyroidectomy due to cosmetic considerations and the shortening of the hospital stay. An endotracheal tube may become obstructed by bending or compression due to changes in patient's position in the preperation for head and neck surgery. Therefore, the use of an armored tube has been increasing for this type of surgery. A new armored tube obstruction was experienced in a 27-years-old female patient with a thyroid adenoma, who underwent an endoscopic thyroidectomy. The swelling of a layer of the inner wall of the new armored tube was detected at about 10 cm, which caused an obstruction of 50% of the radius of the tube. Tracheal laceration also occurred during the operation, which was sutured under endoscopy; however, the stitches became unknotted in the recovery room, but were corrected by exploration.