A memory device is provided. The memory device comprises a substrate, a plurality of word lines, a plurality of conductive regions and at least a shielding plug. The substrate has a memory region and a peripheral region. The word lines are disposed on the substrate and at least a dummy word line disposed in the peripheral region and adjacent to the word lines. The conductive regions are disposed in the substrate and between the word lines respectively. The shielding plug is located on the substrate and adjacent to the dummy word line and between the dummy word line and the word lines and there is no self-aligned source region around the dummy word line.