A memory device including a first conductive line on a substrate and extending in a first horizontal direction; a second conductive line on the first conductive line and extending in a second horizontal direction that is perpendicular to the first horizontal direction; and a memory cell between the first conductive line and the second conductive line, the memory cell including a variable resistance memory layer, a buffer resistance layer, and a switch material pattern, extending in a vertical direction that is perpendicular to the first horizontal direction and the second horizontal direction, and having a tapered shape with a decreasing horizontal width along the vertical direction, wherein at least a part of the variable resistance memory layer and at least a part of the buffer resistance layer of the memory cell are at a same vertical level.