A 72-year-old man was admitted to our hospital due to dysuria and frequent syncope. The patient had been well until the age of 70 years, when he began with these symptoms and neurogenic bladder was diagnosed in the other hospital. On admission, neurological examinations revealed no abnormal findings except blepharoptosis, anisocoria and orthostatic hypotension. Frequent apnea was evident during sleep. Autonomic function tests showed mainly sympathetic postganglionic dysfunction. Brain magnetic resonance imaging showed lacunar infarctions without cerebello-pontine atrophy or abnormal signals of the basal ganglia. We diagnosed pure autonomic failure (PAF) with sleep apnea syndrome (SAS). After starting nasal continuous positive airway pressure (CPAP) for SAS, his sneezing and sleep apnea drastically improved. Interestingly, CPAP also decreased the severity of orthostatic hypotension and syncope. Ambulatory blood pressure monitoring (ABPM) showed remarkable improvement in diurnal fluctuation of blood pressure after CPAP therapy. Although SAS is frequently associated with Shy-Drager syndrome but not with PAF, patients with PAF had been reported to have degenerative changes in the central nervous system overlapping with Shy-Drager syndrome or Lewy body disease. This case raised the possibility that nasal CPAP may be useful for orthostatic hypotension as well as SAS in neurodegenerative diseases.