In neurosurgery, intractable epilepsy, Parkinson’s syndrome, torsion spasms, and intractable pain are called functional disorders. Some functional disorders are ineffective after conservative treatment such as medications and often require surgical treatment and intervention such as surgery. Intractable epilepsy, advanced Parkinson’s syndrome, and torsional spasm can be treated by stereotactic nucleus destruction, deep electrode placement, and epileptic focus excision. Since the early 1990s, our department has been carrying out these procedures, and for more than ten years, we have been focusing on the surgical treatment of functional diseases. At present, we are able to carry out surgical treatment of various types of intractable epilepsy, malignant pain, Parkinson’s syndrome, and torsion spasm with satisfactory results.