A 68-year-old woman presented with a sudden severe headache, vomiting, and disturbed consciousness. She was admitted to the emergency room. Computed tomography (CT) revealed a hemorrhage in the right temporal lobe. Angiography demonstrated a ruptured aneurysm in the right middle cerebral artery (MCA) and an unruptured aneurysm in the left MCA. The subarachnoid hemorrhage was grade 3 (Hunt and Kosnik classification). Emergency craniotomy, clipping of the ruptured aneurysm and removal of the hematoma were performed. The left hemiparesis improved, and the patient was able to walk. We prescribed triazolam (0.25 mg/day) to treat the patient's insomnia. The unruptured aneurysm was additionally clipped on the 15th hospital day. After the second operation, the patient complained of delirium with restlessness, excitement, disorganized behavior, and sleep disturbance. Treatment with thiapride (150 mg/day) did not improve the delirium. We additionally administered Yi-gan san (7.5 g/day) and switched the triazolam to ramelteon (8 mg/day). The Memorial Delirium Assessment Scale score improved dramatically (from 16 at onset to 5 on day 7 and 1 at two months). Yi-gan san is reported to be effective for the treatment of behavioral and psychological symptoms of dementia. Ramelteon, a melatonin receptor agonist, is implicated in the regulation of the sleep-wake cycle. Ramelteon, unlike other hypnotic drugs, does not cause oversedation, rebound insomnia, withdrawal symptoms or dependence. In addition, we have noted no adverse effects, including oversedation or clinically significant changes in laboratory data, during combination therapy. A combination of ramelteon and Yi-gan san may therefore be beneficial in elderly patients with delirium, especially when there is a risk of oversedation.