A vertical memory device includes first gate electrodes spaced apart from each other under a substrate in a first direction substantially perpendicular to a lower surface of the substrate, the first gate electrodes being arranged to have a staircase shape including steps of which extension lengths in a second direction substantially parallel to the lower surface of the substrate gradually increase from an uppermost level toward a lowermost level, second gate electrodes spaced apart from each other under the first gate electrodes in the first direction, the second gate electrodes being arranged to have a staircase shape including steps of which extension lengths in the second direction gradually decrease from an uppermost level toward a lowermost level and a channel extending through the first and second gate electrodes in the first direction.