A 79-year-old woman was admitted to our hospital because of prolonged impaired consciousness and right hemiparesis. She was treated for acute cerebral infarction because her brain magnetic resonance imaging showed extensive cortical lesions similar to acute infarction in diffusion weighted image, fluid attenuated inversion recovery, and T2 weighted images. On the fifth day, she had a focal seizure on the right side. A new lesion during imaging and electroencephalogram abnormality were observed at that time. After the antiepileptic drug treatment was started, her right hemiparesis considered as ictal paresis, confusion, and the magnetic resonance imaging findings gradually improved. There was also an old, irreversible lesion in the left hippocampus, which was considered as the focus of her complex partial seizure. In the elderly, the post-ictal period of confusion, which occurs with complex partial seizure, may be prolonged. In our case, improvement of hemiparesis and confusion occurred after about 2 weeks.