Schwannoma is a benign nerve sheath tumor composed of Schwann cells. A solitary schwannoma in the thorax is not rare, but a patient with Neurofibromatosis type 2 (NF2) and multiple thoracic schwannomas is extremely rare. We report the case of a 27-year-old woman with NF2 and two large schwannomas in her mediastinum and chest wall. We performed thoracic surgery on the patient, but she developed a cerebral hernia immediately after the operation. We report this case in order to analyze the relationship between the operation and cerebral hernia and find a way to prevent this consequence in the future. We conclude that a cranial MRI must be performed for patients with multiple thoracic schwannomas before the surgery. If there is a tumor inside the cranium, the disease in the brain must be treated first to prevent the occurrence of cerebral hernia or hemorrhage.