A semiconductor memory device may include a first electrode and a second electrode, which are spaced apart from each other in a first direction, and a first semiconductor pattern, which is in contact with both of the first and second electrodes. The first semiconductor pattern may include first to fourth sub-semiconductor patterns, which are sequentially disposed in the first direction. The first and fourth sub-semiconductor patterns may be in contact with the first and second electrodes, respectively. The first and third sub-semiconductor patterns may be of a first conductivity type, and the second and fourth sub-semiconductor patterns may be of a second conductivity type different from the first conductivity type. Each of the first to fourth sub-semiconductor patterns may include a transition metal and a chalcogen element.