In a non-volatile memory device and method of manufacturing the same, a device isolation pattern and an active region extend in a first direction on a substrate. A first dielectric pattern is formed on the active region of the substrate. Conductive stack structures are arranged on the first dielectric pattern and a recess is formed between a pair of the adjacent conductive stack structures. A protection layer is formed on a sidewall of the stack structure to protect the sidewall of the stack structure from over-etching along the first direction. The protection layer includes an etch-proof layer having oxide and arranged on a sidewall of the floating gate electrode and a sidewall of the control gate line and a spacer layer covering the sidewall of the conductive stack structures.