An integrated circuit device includes a substrate including active regions, a direct contact electrically connected to a first active region selected from the active regions, a buried contact plug electrically connected to a second active region selected from the active regions, the second active region adjacent to the first active region in a first horizontal direction, and including a conductive semiconductor layer, a bit line extending on the substrate in a second horizontal direction perpendicular to the first horizontal direction and electrically connected to the direct contact, a conductive landing pad extending toward the buried contact plug in a vertical direction, having a sidewall facing the bit line in the first horizontal direction, and including a metal, and an outer insulating spacer between the bit line and the conductive landing pad, in contact with the sidewall of the conductive landing pad, and spaced apart from the buried contact plug.