Unilateral vocal cord palsy which is associated with laryngeal trauma is not uncommon event. In a 42-year-old male, a cricoid cartilage fracure had been developed after blunt trauma. The endoscopic findings showed contusion and diffuse swelling around the left arytenoid and false cord. During phonation, the mobility of left side true vocal cord was decreased. There were no level difference and displacement of the left side arytenoid. We used the laryngeal electromyography (LEMG) to make a differential diagnosis between the cricoarytenoid joint dislocation and the injury of recurrent laryngeal nerve. At the right thyroarytenoid muscle and cricothyroid muscle, the findings of LEMG were normal. But the amplitude and frequency during phonation were decreased (partial denervation) at the left thyroarytenoid muscle. LEMG is a very useful method to predict the diagnosis of vocal cord palsy.