Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare inborn error of neurotransmitter biosynthesis that leads to a combined deficiency of catecholamines and serotonin and is characterized by global developmental delay, involuntary movements, and autonomic dysfunction. We report the case of an 11-year-old male patient with AADC deficiency who also had epileptic spasms and generalized tonic seizures with asymmetrical features, in addition to frequent involuntary non-epileptic movements. The clinical manifestation of the epileptic attacks apparently resembled that of non-epileptic attacks. It was difficult to differentiate between both attacks without the help of an ictal electroencephalographic study. The epileptic attacks were finally controlled by appropriate antiepileptic drugs. Because an association with epileptic seizures is uncommon in AADC deficiency, some cases may have been regarded as involuntary non-epileptic movements. This indicates that the differentiation of epileptic attacks from non-epileptic ones is indispensable for the adequate treatment of patients with AADC deficiency.