A semiconductor memory device includes a third insulating pattern and a first insulating pattern on a substrate, the third insulating pattern and the first insulating pattern being spaced apart from each other in a first direction that is perpendicular to the substrate such that a bottom surface of the third insulating pattern and a top surface of the first insulating pattern face each other, a gate electrode between the bottom surface of the third insulating pattern and the top surface of the first insulating pattern, and including a first side extending between the bottom surface of the third insulating pattern and the top surface of the first insulating pattern, and a second insulating pattern that protrudes from the first side of the gate electrode by a second width in a second direction, the second direction being different from the first direction.