A semiconductor memory device includes a plurality of functional bit lines, at least one dummy bit line, and a dummy bit line selection unit. The at least one dummy bit line is adjacent to an outermost bit line of the functional bit lines. The dummy bit line selection unit activates the at least one dummy bit line in response to a selection control signal of one of the plurality of functional bit lines that is not adjacent to the at least one dummy bit line. The semiconductor memory device may ensure a photo margin, so that the pattern size of the functional bit lines can be made uniform.