Clinical laryngostroboscopic study was made on 56 cases of voice disorders. Stroboscopy is very useful for clinical evaluation of the abnormality in mode of vocal cord vibration. With good trained eyes, one can detect changes in physical parameters. The author observed glottic symmetry, regularity, amplitude, wave and glottic closure by the use of Pentax laryngostroboscope LS-1A with the following results. 1) Non-symmetry, regularity, non-glottic closure shows high in number, amplitude and wave revealed decrease in percent. 2) Postoperative laryngostroboscopic test shows incomparably superior to that of preoperative cases.