Mycoplasma pneumoniae is a common agent causing tracheobronchitis and pneumonia and its most frequent extrapulmonary complications include central nervous system (CNS) manifestations. Acute disseminated encephalomyelitis (ADEM) is a rare neurological complication due to M. pneumoniae. We experienced a case of ADEM from M. pneumoniae infection, diagnosed by cold hemagglutinin test and brain magnetic resonance imaging (MRI). The patient was almost completely cured with intravenous immunoglobulin therapy. We therefore report the case with a review of the literature.