A semiconductor device includes an active pattern array including active patterns on a substrate; a first contact structure on a central portion of each active pattern; a bit line structure on the first contact structure; a second contact structure on an end of each active pattern; a third contact structure on the second contact structure; and a capacitor electrically connected to the third contact structure, wherein the active pattern array includes active pattern rows spaced apart from each other in a second direction parallel the substrate, the active pattern rows include active patterns spaced apart from each other in a first direction parallel to the substrate, the active patterns extend in a third direction having an acute angle with the first/second directions, the active patterns in the rows are aligned in the first direction, and the second contact structure has a rectangular shape in a plan view.