A heat pump system is provided. The heat pump system may include a compressor that compresses a refrigerant, a condenser that condenses the refrigerant, an expansion device that decompresses the refrigerant, and an evaporator that evaporates the refrigerant. The condenser may include a first heat exchanger of a first shell and tube heat exchanger and a second shell and tube heat exchanger. The evaporator may include a second heat exchanger of the first shell and tube heat exchanger and the second shell and tube heat exchanger. The first shell and tube heat exchanger or the second shell and tube heat exchanger may include a shell, in which the refrigerant may be introduced, a plurality of tubes disposed within the shell and into which a fluid heat-exchanged with the refrigerant may flow, two inlet/outlets disposed on a first side of the shell, and one inlet/outlet disposed on a second side of the shell.