Idiopathic normal pressure hydrocephalus (iNPH) is a syndrome characterized by ventricular dilatation due to disturbed cerebrospinal fluid (CSF) circulation, accompanied by gait disturbance, dementia and/or urinary incontinence without causative disorders. With the aging of Japanese society, the number of patients is increasing, requiring diagnostic and therapeutic guidelines for the improvement of the patients' quality of life and social care. Under such conditions, this project was made as the prospective study of iNPH on Neurological Improvement (SINPHONI ). This study aims 1) to establish methods for non-invasive diagnosis of iNPH, and 2) to demonstrate therapeutic outcome of shunting operation by Codman Hakim programmable valve (CHPV). In this protocol, the evaluation of validity on MRI, tap test, CT cisternography, and CBF (3D-SSP) will be done in the diagnosis, and manual of initial setting pressure in CHPV for prevention of overdrainage problems will be estimated by modified Rankin scale (as primary endpoint) and some another scales during 1 year.