A memory device includes a first memory cell array, a second memory cell array disposed in a first direction with respect to the first memory cell array, a first contact plug extending in the first direction through the first memory cell array, and a second contact plug extending in the first direction through the second memory cell array. The first memory cell array includes first electrode layers stacked in a first direction, and a first semiconductor pillar extending through the first electrode layers in the first direction. The second memory cell array including second electrode layers stacked in the first direction, and a second semiconductor pillar extending in the first direction through the second electrode layers. The first contact plug is electrically connected to the first semiconductor pillar, and the second contact plug is electrically connected to the second semiconductor pillar and the first contact plug.