A heat pump system for a vehicle according to an embodiment of the present disclosure may control a temperature of a battery module by using one chiller in which a refrigerant and a coolant are heat-exchanged, may recover waste heat generated from an electrical component and the battery module to use it for indoor heating, thereby improving the heating performance and efficiency, and may increase a flow rate of the refrigerant by applying a gas injection part that selectively operates in a heating mode of a vehicle, thereby maximizing heating performance.