Mr. A was a 19-year-old right-handed male high school student with a 4-year history of DSM-IV paranoid schizophrenia. At age 15, he presented with auditory hallucinations, persecutory delusions, delusions of reference, and decreased social interaction. Sulpiride, 400 mg/day, was administered for 2 years, but decreased social interaction and delusions of reference remained. We replaced sulpiride, 400 mg/day, with aripiprazole, 12 mg/day. This switching led to complete remission of his schizophrenic symptoms and he had no adverse event. Afterward he studied hard to take a university entrance examination. Eight months after aripiprazole therapy, he complained that it was hard to write because of a stiffening of his right hand, and these episodes occurred whenever he was willing to write. He showed tight grip of the pen, hyperflexion at wrist joint, flexion at elbow joint, and abduction at shoulder joint when writing. He had no abnormal findings on hematology tests, biochemistry tests, magnetic resonance imaging of the brain, and electroencephalography. He had no other movement disorders except for these symptoms. He also had no family history of dystonia or other movement disorders. His symptoms were diagnosed by neurologists as a writer's cramp. The dosage of aripiprazole was gradually decreased and completely discontinued without recurrence of his psychosis. Despite withdrawal of aripiprazole, he still has these symptoms during 6-month follow up.