A semiconductor device includes: a substrate having a plurality of active regions; a plurality of bit lines extending in a first direction, the plurality of bit lines being separate from the substrate with an insulating layer therebetween; a plurality of first insulating lines extending in a second direction that is different from the first direction, wherein the plurality of first insulating lines intersect the plurality of bit lines and have upper surfaces having levels which are higher than those of upper surfaces of the plurality of bit lines relative to the substrate; and a plurality of first contact structures connected to the plurality of active regions, the plurality of first contact structures being disposed in an area defined by the plurality of bit lines and the plurality of first insulating lines.