A resistance-variable memory device includes memory cells, a high voltage circuit, a precharging circuit, a bias circuit, and a sense amplifier. Each memory cell may, for example, include a resistance-variable material and a diode connected to a bitline. The high voltage circuit provides a high voltage from a power source. The precharging circuit raises the bitline up to the high voltage after charging the bitline up to the power source voltage. The bias circuit supplies a read current to the bitline using the high voltage. The sense amplifier compares a voltage of the bitline with a reference voltage by means of the high voltage.