A heat pump system for a vehicle may include a cooling apparatus including a radiator, a first water pump, a first valve, and a reservoir tank which are connected through a coolant line, and configured to circulate a coolant in the coolant line to cool at least one electrical component provided in the coolant line; a battery cooling apparatus configured to include a battery coolant line connected to the reservoir tank through a second valve, and a second water pump and a battery module which are connected through the battery coolant line to circulate the coolant in the battery module; and a heating apparatus including a heating line connected to the coolant line through a third valve to heat a vehicle interior by use of a coolant and a third water pump provided on the heating line, and a heater.