In this report, we describe the case of two patients with Bickerstaff's brainstem encephalitis (BBE) who developed delirium manifested as emotional incontinence, restlessness, and aggressive behavior from disease onset. Serum anti-GQ1b and anti-GT1a IgG antibodies were detected in both patients. When unusual psychiatric symptoms are observed, in addition to acute ophthalmoplegia and ataxia, neurologists should take into account the possibility of BBE. Brain MRI findings were normal in both patients and SPECT was performed on only patient 1. SPECT of patient 1 showed reversible hypoperfusion in the brainstem, bilateral thalami, and medial frontal lobe. Brain SPECT appears to be useful for detecting lesions of the brainstem as well as the basal ganglia or cerebrum in BBE.