A memory device includes a cell wafer including a memory cell array; and a peripheral wafer including a row control circuit, a column control circuit and a peripheral circuit which control the memory cell array, and stacked on and bonded to the cell wafer in a first direction. The peripheral wafer includes a first substrate having a first surface and a second surface which face away from each other in the first direction; a first logic structure disposed on the first surface of the first substrate, and including the row control circuit and the column control circuit; and a second logic structure disposed on the second surface of the first substrate, and including the peripheral circuit.