In a vehicle air conditioner device of a heat pump system, control of an air mix damper is appropriately performed in each operation mode, thereby achieving efficient vehicle interior air conditioning. The vehicle air conditioner device includes an air mix damper 28 to adjust a ratio at which air in an air flow passage 3 passed through a heat absorber 9 is to be passed through a radiator 4. In a cooling mode, a controller controls the air mix damper 28 to adjust the ratio at which the air is to be passed through the radiator 4 on the basis of one, any combination, or all of a target outlet temperature, a temperature of the radiator and a temperature of the heat absorber, and in a heating mode, the controller controls the air mix damper 28 to pass all the air in the air flow passage 3 through the radiator 4.