A semiconductor device includes a plurality of insulation patterns and a plurality of gates alternately and repeatedly stacked on a substrate, a channel pattern extending through the gates in a first direction substantially perpendicular to a top surface of the substrate, a semiconductor pattern between the channel pattern and the substrate, and a conductive pattern between the channel pattern and the semiconductor pattern. The conductive pattern electrically connects the channel pattern to the semiconductor pattern. The conductive pattern contacts a bottom edge of the channel pattern and an upper surface of the semiconductor pattern.