A semiconductor memory device is disclosed. The device includes a peripheral circuit structure on a substrate, a semiconductor layer on the peripheral circuit structure, an electrode structure on the semiconductor layer, the electrode structure including electrodes stacked on the semiconductor layer, a vertical channel structure penetrating the electrode structure and being connected to the semiconductor layer, a separation structure penetrating the electrode structure, extending in a first direction, and horizontally dividing the electrode of the electrode structure into a pair of electrodes, an interlayered insulating layer covering the electrode structure, and a through contact penetrating the interlayered insulating layer and being electrically connected to the peripheral circuit structure.