A memory device is provided. The memory device includes a substrate, a first interface connector, a second interface connector and a plurality of memory chips. The substrate includes a first edge, a second edge, a third edge and a fourth edge. The first interface connector is disposed on the first edge, wherein the first interface connector includes a plurality of first edge-board contacts, and the first edge-board contacts extend toward a first direction. The second interface connector is disposed on the second edge, the second interface connector includes a plurality of second edge-board contacts, and the second edge-board contacts extend toward a second direction. The memory chips are disposed on the substrate, wherein the second interface connector is located between the memory chips and the first interface connector in the first direction.