A non-volatile memory device may include a semiconductor substrate, a stack structure and a source structure. The stack structure may be formed on the semiconductor substrate. The source structure may be formed in a slit configured to divide the stack structure. The source structure may include a sealing layer, a source liner, a gap-filling layer and a source contact pattern. The sealing layer may be formed on an inner wall of the slit. The source liner may be formed on a surface of the sealing layer and a bottom surface of the slit. The gap-filling layer may be formed in the slit. The source contact pattern may be formed on the gap-filling layer in the slit. The source contact pattern may be electrically connected with the source liner.