a memory device includes a data line sense amplifier configured to receive a sense amplifying power source voltage and a sense amplifying ground voltage through a sense amplifying power source line and a sense amplifying ground line , respectively , and sense - amplify data loaded on a pair of data lines , and a pre - charging unit configured to pre - charge and equalize the sense amplifying power source line and the sense amplifying ground line with a sense amplifying pre - charge voltage , generate the sense amplifying pre - charge voltage by voltage dividing the sense amplifying power source voltage and the sense amplifying ground voltage through a voltage dividing path including the sense amplifying power source line and the sense amplifying ground line , and apply the sense amplifying power source voltage to the sense amplifying power source line and the sense amplifying ground voltage to the sense amplifying ground line in response to a sense amplifying pre - charge control signal .