We report a case of right tentorium subdural hematoma (SDH) in a 72-year-old man a few days after he visited a sanitas per aqua (SPA) facility. He had directed high-pressure water onto his head and neck. The patient was admitted to the emergency room during his 3 rd day of severe throbbing and generalized headache. Cerebral computed tomography revealed a high-density SDH over the right tentorium. This is the first reported case of SPA-related SDH. Neurologists might consider the possibility that SPA use may be a factor in SDH or unexplained neurologic events in otherwise healthy persons.