A semiconductor memory device includes a substrate including a cell region, a core region, and a boundary region between the cell region and the core region, a boundary element isolation layer in the boundary region, the boundary element isolation layer being in a boundary element isolation recess and including first and second boundary liner layers extending along a profile of the boundary element isolation recess and a first gate structure on the core region and at least a part of the boundary element isolation layer, wherein the first gate structure includes a first high dielectric layer, and a first gate insulating pattern below the first high dielectric layer, with a top surface of the substrate being a base reference level, the first gate insulating pattern does not overlap a top surface of the first boundary liner layer, and wherein the first gate insulating pattern includes a first_1 gate insulating pattern between a top surface of the second boundary liner layer and a bottom surface of the first high dielectric layer, and a first_2 gate insulating pattern disposed a top surface of the core region and a bottom surface of the first high dielectric layer.