A heating temperature is appropriately estimated according to an operation mode to achieve comfortable vehicle interior air conditioning. A vehicular air conditioning device 1 includes a compressor 2, an air flow passage 3, a radiator 4 for heating air to be supplied to a vehicle interior, a heat absorber 9 for cooling the air to be supplied to the vehicle interior, and a heat pump controller. The heat pump controller calculates a heating temperature TH being the temperature of air on a leeward side of the radiator and use the heating temperature in control, and calculates the heating temperature TH using an estimation formula which differs depending on the operation mode.