A method of manufacturing a semiconductor memory device includes forming bit line structures extending in a first horizontal direction on a substrate, and insulating spacer structures covering opposite sidewalls of each bit line structure, forming a preliminary buried contact material layer and a mold layer to respectively fill lower and upper portions of a space between a pair of insulating spacer structures, patterning the mold layer and the preliminary buried contact material layer into mold patterns spaced apart from each other in a second horizontal direction and buried contacts spaced apart from each other in the second horizontal direction, forming insulating fences among the mold patterns separated from each other and among the buried contacts separated from each other, removing the mold patterns to expose the buried contacts, and forming landing pads on the exposed buried contacts, each landing pad connected to a corresponding one of the exposed buried contacts.