A highly integrated semiconductor memory device includes a substrate, a plurality of vertical pillars above the substrate, a plurality of connection lines extending over the vertical pillars, a plurality of lower via plugs provided above the vertical pillars and connecting the vertical pillars to the connection lines, a dummy connection line provided at a same level as the connection lines with respect to a main surface of the substrate, and a dummy via plug connected to a lower surface of the dummy connection line and having a different height than each of the lower via plugs. The vertical pillars, the connection lines, the lower via plugs are provided in a cell region, and the dummy connection line and the dummy via plug are provided in a dummy region.