We present herein the case of a patient with a focal orbital frontal lesion on magnetic resonance imaging (MRI), but an insular onset of seizures. A 15-year-old boy suffered from hypermotor seizures for 9 years. In his seizures, he initially had a sensation that sounds were distant, and then his consciousness became impaired. After a short period of tonic activity, violent activities occurred, such as kicking or gripping some objects and shaking. MRI showed a focal cortical abnormality in the right orbital frontal lobe. [(18)F]FDG-PET revealed diffuse hypometabolism in the right frontal lobe, especially in the same site as the cortical lesion on MRI. The seizure onset zone was localized in the right anterior insula by intracranial recording. A resection of the right anterior insula and a partial disconnection of the frontal lobe were performed, rendering the patient seizure-free.