A vertical memory device includes a first gate structure on a substrate, the first gate structure including first gate electrodes spaced from each other in a first direction and stacked in a staircase shape, a second gate structure on the first gate structure and including second gate electrodes spaced from each other in the first direction and stacked in the staircase shape, a channel extending through the first and second gate structures, and a contact plug extending in the first direction through the first and second gate structures, wherein second steps at end portions of the second gate electrodes overlap first steps at end portions of the first gate electrodes, and wherein the contact plug extends through at least one of the first steps and through at least one of the second steps, while being electrically connected only to the first steps or to the second steps.