A 48-year-old female presented with vertiginous feeling and behavior disturbance. Computed tomography showed an arachnoid cyst on the left cerebral convexity. Single photon emission computed tomography revealed decreased cerebral blood flow (CBF) in the left frontal lobe. The Wechsler Memory Scale-Revised test demonstrated memory dysfunction. The arachnoid cyst was partially removed. Disturbances in CBF and behavior disappeared postoperatively. Local ischemia induced by compression due to arachnoid cyst may cause memory dysfunction and behavior disturbance. Neuropsychometric examination is useful for the evaluation of such symptoms.