A semiconductor device comprises a plurality of pillars on a semiconductor substrate, and a support pattern in contact with at least one side surface of each of the pillars. The support pattern connects the pillars with one another. The support pattern includes a plurality of support holes that expose side surfaces of the pillars. The support holes includes a first support hole and a second support hole that are spaced apart from each other. The pillars have circular cross-sections. A ribbon-like hexagon is obtained in a plan view when connecting an inner sidewall of the first support hole with central points of the cross-sections of the pillars exposed through the first support hole.