Disclosed herein is a heat pump system for a vehicle which includes an evaporator mounted on a cold air passageway inside an air-conditioning case, a condenser mounted on a warm air passageway, a first blower mounted at an inlet side of the cold air passageway of the air-conditioning case, a second blower mounted at an inlet side of the warm air passageway and an intake duct mounted between the first blower and the second blower to supply indoor air and outdoor air to the first blower and the second blower respectively, thereby maximizing space efficiency because using just one intake duct for the two blowers, and reducing the size and manufacturing costs of the heat pump system.