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.