A semiconductor device includes bit line structures on a substrate, the bit line structures extending along a first direction and being spaced apart from each other along a second direction perpendicular to the first direction, contact plugs spaced apart from each other along the first direction and being on active regions of the substrate between adjacent bit line structures, a linear spacer on each longitudinal sidewall of a bit line structure, landing pads on the contact plugs, respectively, the landing pads being electrically connected to the contact plugs, respectively, and landing pads that are adjacent to each other along the first direction being offset with respect to each other along the second direction, as viewed in a top view, a conductive pad between each of the contact plugs and a corresponding active region, a vertical axes of the conductive pad and corresponding active region being horizontally offset.