A memory device including: a memory cell array disposed in a first semiconductor layer, the memory cell array including a plurality of wordlines extended in a first direction and stacked in a second direction substantially perpendicular to the first direction; and a plurality of pass transistors disposed in the first semiconductor layer, wherein a first pass transistor of the plurality of pass transistors is disposed between a first signal line of a plurality of signal lines and a first wordline of the plurality of wordlines, and wherein the plurality of signal lines are arranged at the same level as a common source line.