A semiconductor device includes a channel structure arranged on a substrate and extending in a first direction perpendicular to a top surface of the substrate, the channel structure including a channel layer and a gate insulating layer; a plurality of insulating layers arranged on the substrate and surrounding the channel structure, the plurality of insulating layers spaced apart from each other in the first direction; a plurality of first gate electrodes surrounding the channel structure; and a plurality of second gate electrodes surrounding the channel structure. Between adjacent insulating layers from among the plurality of insulating layers are arranged a first gate electrode from among the plurality of first gate electrodes spaced apart along the first direction from a second gate electrode from among the plurality of second gate electrodes.