We describe a 49-year-old female patient with neuro-Behçet's disease (NBD) with acute onset of fever and symptoms of dementia. High-dose glucocorticoid was partially effective for cognitive impairment, and infliximab, an anti-TNF-α antibody, gradually improved the symptoms. An analysis of cytokines showed that IP-10 in the cerebrospinal fluid was higher than that in the peripheral blood, and both decreased after treatment. This is the first known case of NBD wherein the patient with acute onset of dementia responded to a treatment with infliximab. In glucocorticoid-resistant patients, it is important to consider the introduction of infliximab to prevent irreversible brain dysfunction.