Oral cenesthopathy is a somatic delusion in the oral area and categorized as delusional disorder, somatic type. Patients experience unusual and annoying sensations in the mouth such as pulling on the teeth, moving teeth, overly secreting mucus, tingling and pain, and so on, without a somatic base. The condition is usually treatment-resistant and impairs patients' quality of life. We report a case of oral cenesthopathy successfully treated with the modified electroconvulsive therapy, who demonstrated altered regional cerebral blood flow before and after the treatment detected by single-photon emission computed tomography.