Various types of cognitive and behavioral impairments occur after traumatic brain injury. We present a case exhibiting psychotic symptoms such as irritability, dysphoria, anxiety and insomnia with severe brain dysfunction due to a right temporal lobe contusion incurred in a traffic accident. The patient did not sufficiently respond to rehabilitation or treatment with any pharmacotherapy. In the present case, aripiprazole dramatically improved the patient's symptoms and cognitive function. We evaluated the case using the Wechsler Adult Intelligence Scale-Revised and the Wechsler Memory Scale Revised between baseline and 5 years later.