Phase change memory device and program method thereof

A phase change memory device and a program method thereof are provided to reduce program time by using a pump circuit to increase current supply capability of a write driver. A memory cell has a phase change material. A write driver(400) supplies a write current to the memory cell. A pump circuit(500) increases current supply capability of the write driver during a program operation. The pump circuit operates in advance before the program operation in response to an external control signal. The pump circuit includes a subsidiary pump(510) operating before the program operation, a main pump(520) operating during the program operation, and a pump controller(530) controlling the operation of the subsidiary pump and the main pump in response to the external control signal.