A stacked memory device may include a substrate, a plurality of memory groups sequentially stacked on the substrate, each memory group including at least one memory layer, a plurality of X-decoder layers, at least one of the plurality of X-decoder layers being disposed between every alternate neighboring two of the plurality of memory groups, and a plurality of Y-decoder layers disposed alternately with the plurality of X-decoder layers, at least one of the plurality of Y-decoder layers being disposed between every alternate neighboring two of the plurality of memory groups.