Heat Pump System for Vehicle

An embodiment is a heat pump system for a vehicle, including a first cooling device including a first radiator, a first water pump, and a first valve connected by a first coolant line, a second cooling device including a second radiator and a second water pump connected by a second coolant line, a third cooling device including a third coolant line connected to the second cooling device through a first valve, a third water pump provided on the third coolant line, and a battery module and, a chiller provided on the third coolant line, and a gas injection device configured to selectively expand a refrigerant supplied from an internal condenser included in an air conditioner and supply the expanded refrigerant to a heat exchanger of the air conditioner, and selectively supply a portion of the refrigerant to a compressor.