A phase change random access memory device includes: a sense amplifier driving unit configured to compare an input voltage applied through an input signal line with a reference voltage and amplify an output signal in response to the comparison result; an input unit configured to receive an input signal from the input signal line and transmit the received signal to the sense amplifier driving unit; and a coupling prevention unit including a plurality of MOS transistors sharing a bulk bias, coupled between the sense amplifier driving unit and the input unit, and configured to control a sensing margin in response to a level of the input signal.