Cortical blindness is characterized by visual sensation loss with retention of pupillary reaction to light, and a normal fundoscopic examination. The suggested causes are emboli, profound hypotension, anemia, and infarction of watershed areas in the parietal or occipital lobe. We experienced a case of cortical blindness with severely reduced visual acuity after penile cancer surgery under general anesthesia. In the acute stage, visual acuity was slightly improved, but over the course of several months, no further improvement in visual acuity occurred. In this case there was no severe hypotension or anemia during the operation. Two days after the operation, electroencephalography (EEG) was performed during the period of blindness and the recording obtained was abnormal, with no alpha rhythm. Biparieto-occipital lucency was found by magnetic resonance imaging (MRI). Therefore parieto-occipital infarction due to seizure, embolus, or thrombosis could be considered a possible etiology. We concluded that cortical blindness can unexpectedly develop perioperatively and postoperatively, and that close monitoring of the patient and adequate management are essential.