Normal pressure hydrocephalus after radiosurgery for meningioma has rarely been reported. We report such a case and discuss the role of radiosurgery in the development of hydrocephalus. A 75-year-old man with a growing tumor underwent linac-based radiosurgery. The tumor received 16 Gy to the 80% isodose line. He exhibited the triad of symptoms of normal pressure hydrocephalus and became bedridden three months after radiosurgery. Dilated ventricles were demonstrated with MRI. Examination of the cerebrospinal fluid revealed a high level of protein. The patient underwent a ventriculoperitoneal shunt and recovered well.