The cerebellum is one of the main targets in the central nervous system for autoimmunity. Immune-mediated cerebellar ataxias include gluten ataxia, GAD antibody-associated cerebellar ataxia, Hashimoto's encephalopathy, and paraneoplastic cerebellar degeneration. Autoimmune cerebellar ataxia may be of either insidious or subacute onset, and vertigo or transient neurological symptoms occur in some patients before the onset of the disease, in contrast to spinocerebellar degeneration. If autoimmune cerebellar ataxia is suspected, early diagnosis and introduction of treatment are very important. For diagnosis, testing for gliadin antibody, TG6 antibody, GAD antibody, thyroid antibody, and anti-neuronal antibodies, including mGluR1, is useful. Magnetic resonance imaging voxel-based morphometry is also useful because it can detect cortical cerebellar atrophy of autoimmune cerebellar ataxia, different from spinocerebellar ataxia. As for treatment, it is important to remove autoimmune triggering factors (e.g.,dietary gluten or neoplasm). When the ataxia symptoms are causing hindrances in the daily life, it is worth considering immunotherapy including IVIg, steroid therapy and so on.