A non-volatile memory device comprises a semiconductor substrate having source/drain regions formed at both ends of a channel region, a gate structure forming an offset region by being separated a predetermined distance from the source region and comprising a charge accumulation region and a control gate sequentially deposited in the channel region to at least partially overlap the drain region, and a spacer arranged at each of both side walls of the gate structure. A threshold voltage value of the offset region changes depending on a dielectric constant of the spacer.