A memory device is provided. The memory device includes a plurality of stack structures, a plurality of first stepped contacts, and a plurality of second stepped contacts. Each of the stack structures extends in a first direction, and includes a first semiconductor layer and a second semiconductor layer. The second semiconductor layer is disposed above the first semiconductor layer. Each of the first stepped contacts extends in a second direction, and a bottom surface thereof is electrically connected to the first semiconductor layers of an i+1th stack structure and an i+2th stack structure, wherein i is an odd number. Each of the second stepped contacts extends in the second direction, and a bottom surface thereof is electrically connected to the second semiconductor layers of an nth stack structure and the i+1th stack structure. The first direction is different from the second direction.