A semiconductor memory device may include a bit line extending in a first direction, a first conductive pattern extending in a second direction intersecting the first direction, a semiconductor pattern connecting the bit line and the first conductive pattern, a second conductive pattern including an insertion portion in the first conductive pattern, and a dielectric layer between the first conductive pattern and the second conductive pattern. The insertion portion of the second conductive pattern may have a width which increases as a distance from the semiconductor pattern increases.