Atonic seizures exhibits loss of postural tone, resulting in head drops or falling. When this event is extremely brief, It has been known as a drop attack. Atonic seizure are firmly placed under the category of generalized seizures. However, a various phenomena satisfying the above description has been recognized in patients with partial seizures. A 13-year-old girl had brief episodes of drop attacks. She complained of weakness of both legs in the absence of consciousness loss. These episodes occurred at a frequency of 4 or 5 time per day for 1 year. Her developmental and physical examinations were normal. Also, the brain MRI was normal. However, her Interictal EEG showed the repetitive spike and wave complexes on C(z) electrode. She was controlled completedly by antiepileptic drungs. We report a patient who suffered from focal atonic seizures characterized by drop attack.