A vertical memory device includes gate electrodes on a substrate and a channel. The gate electrodes are spaced apart from each other in a vertical direction substantially perpendicular to an upper surface of the substrate. The channel extends through the gate electrodes, and includes a first portion, a second portion and a third portion. The second portion is formed on and connected to the first portion, and has a sidewall slanted with respect to the upper surface of the substrate so as to have a width gradually decreasing from a bottom toward a top thereof. The third portion is formed on and connected to the second portion.