The present invention relates to a heat pump system for a vehicle, which can independently use waste heat of an engine just as a heat source by separating a heat generation part from a heat absorption part in the heat pump system using a water-cooled condenser, and reduce a length of a loop by separating a high temperature cooling water loop. The heat pump system for a vehicle includes: a first cooling water line for circulating cooling water by connecting a vehicle driving part and a chiller with each other; a second cooling water line disposed in an air-conditioning case for circulating cooling water by connecting a heater core used for heating the interior of the vehicle and a water-cooled condenser with each other; and a valve disposed between the first cooling water line and the second cooling water line. The first cooling water line and the second cooling water line are operated independently if the valve is arranged in a first manner, and the first cooling water line and the second cooling water line are in a serial connection if the valve is arranged in a second manner.