A semiconductor memory device includes an active region protruding from a substrate. The active region includes first and second doped regions therein and a trench therein separating the first and second doped regions. A buried gate structure extends in a first direction along the trench between first and second opposing sidewalls thereof. A conductive interconnection plug is provided on the first doped region adjacent the first sidewall of the trench, and a conductive landing pad is provided on the second doped region adjacent the second sidewall of the trench. The landing pad has a width greater than that of the second doped region of the active region along the first direction. A conductive storage node contact plug is provided on the landing pad opposite the second doped region. The storage node contact plug has a narrower width than the landing pad along the first direction.