We studied the topographical ventilatory motion and electrical muscle activity (EMG) of intercostal muscle within the rib cage for the patients complaining dyspnea produced mostly by their postural changes. There were inappropriateness between the rib cage motion and EMG and this inappropriateness was closely related to a sensation of dyspnea. We could relieve partly dyspnea by applying the negative pressure ventilator, because of prevention of a distortion of rib cage. Based on these clinical observation, we concluded that one of mechanism to sense dyspnea was the inappropriateness between motion and electrical muscle activity within the rib cage.