A heat pump system for a vehicle includes a cooling apparatus configured to circulate a coolant in a coolant line to cool at least one electrical component provided in the coolant line, a battery cooling apparatus configured to circulate the coolant in the battery module, a heating apparatus configured to heat a vehicle interior by using the coolant, and a chiller configured to adjust a temperature of the coolant by heat-exchanging the coolant with a refrigerant, wherein the chiller is connected to the chiller connection line through a third valve provided in the coolant line between the radiator and the second valve, and the reservoir tank is provided in the coolant line between the radiator and the second valve, and is connected to the supply line connecting a first valve and a first water pump through a supply line.