The binding of anti-GD1b IgG antibody to the cerebellar granular area or spinocerebellar Ia fibers in the peripheral nerves may cause the prominent cerebellar ataxia, mild quadriparesis and sensory dominant neuropathy. A 31-year woman presented with severe cerebellar ataxia and prominent apogeotropic positional nystagmus/vertigo. Increased anti-GD1b antibody IgG in her serum was noted. 18F-flurodeoxyglucose positron emission tomography (FDG-PET) showed decreased uptake in cerebellum. It is the first case of central positional nystagmus with anti-GD1b IgG antibody.