Oxidative neurodegeneration causes various neuronal diseases including Alzheimer's disease, Parkinson's disease, and Huntington's disease. This study aimed to demonstrate the protective effect of leaf extracts of Allium senescens on 6-hydroxydopamine (6-OHDA)-stressed SH-SY5Y cells, known as an optimal cell for neurotoxic research. Levels of apoptotic markers were evaluated using quantitative polymerase chain reaction (qPCR) and flow cytometry. The localization of apoptotic cells in vivo was analyzed using whole-mount immunochemistry and the terminal deoxynucleo-tidyl transferase dUTP nick end labeling assay. Additionally, reactive oxygen species (ROS) pro-duction was estimated using flow cytometry. 6-OHDA induced ROS production in neuroblast cells and in vivo, but treatment with the extract protected against the 6-OHDA-induced increase in ROS levels. Under oxidative stress, the extract performs three protective functions: decreases ROS production, prevents mitochondrial apoptosis, and protects the central and ventral nervous systems. These results also suggest that the extract can be useful for the development of functional foods for the prevention of neural damage due to oxidative stress.