Phase-change memory device capable of maintaining constant resistance range and method thereof

A phase-change memory device is provided, which can maintain contact resistance range even though the size of a contact area of a phase-change material and a bottom contact differs in unit cells. A write driver(720) receives data and applies the data to a phase-change memory cell, and applies a sub write current to the phase-change memory cell in response to a first or the nth current control signal. A data sensing part(730) outputs a logic value of the data stored in the phase-change memory cell as a cell data signal by sensing the stored data. A comparison part(740) judges whether the data applied to the phase-change memory cell is equal to the data stored in the phase-change memory cell in response to the cell data signal. And a pulse control unit(750) generates the first or the nth current control signal in response to the detection signal and the pulse signal. A latch unit(760) latches the data applied to the phase-change memory cell.