Plasma cell myelomas generally manifest as bone or soft-tissue tumors with variable mass effects, pain, and infiltrative behavior. Extramedullary involvement occurs most commonly in the spleen, liver, lymph nodes, and kidneys, but intracranial involvement in plasma cell myeloma is a rare extramedullary manifestation. These authors recently encountered a case of intracranial involvement of plasma cell myeloma. A 69-year-old man was hospitalized for headache and mental changes. Brain CT showed subdural hemorrhage caused by plasma cell myeloma. Plasma cell myeloma with intracranial involvement has poor prognosis, and the patient in this case died from acute complications, such as subdural hemorrhage. Based on this case report, it is suggested that more effective treatment regimens of plasma cell myeloma with intracranial involvement be developed. Moreover, a screening method and decision on the appropriate time for intracranial involvement are needed for plasma cell myeloma patients.