There is disclosed a vehicle air conditioner device of a so-called heat pump system to accurately perform efficient and comfortable heating of a vehicle interior. The vehicle air conditioner device includes a heating medium circulating circuit 23 which heats air to be supplied from an air flow passage 3 to a vehicle interior. A controller calculates a required heating capability TGQhtr of the heating medium circulating circuit to complement a shortage of an actual heating capability Qhp to a required heating capability TGQ of a radiator 4. The controller calculates a decrease amount ΔQhp of the actual heating capability Qhp from a difference ΔTXO between a refrigerant evaporation temperature TXO of an outdoor heat exchanger 7 and a refrigerant evaporation temperature TXObase in non-frosting, and adds the decrease amount ΔQhp to the required heating capability TGQhtr to execute the heating by the heating medium circulating circuit.