A data output driver of a semiconductor memory device can minimize a difference in slew rate of an output signal according to a selected bit organization. The data output driver includes a pull-up driver and a pull-down driver. The pull-up driver pulls up an output terminal and the pull-down driver pulls down the output terminal. In particular, current driving capabilities of the pull-up driver and/or the pull-down driver are changed in response to bit organization information signals of the semiconductor memory device.