There is provided a vehicle air conditioning device of a heat pump system which improves comfortability when changing to heating only by an auxiliary heating device. The device includes a heating medium circulating circuit 23 to heat air to be supplied from an air flow passage 3 to a vehicle interior, and when shifting to the heating of the vehicle interior only by the heating medium circulating circuit 23 in a heating mode, a controller executes a shifting control to increase a heating capability of the heating medium circulating circuit 23 prior to stopping a compressor 2 and decrease a heating capability of a radiator 4 in accordance with the increase of the heating capability of the heating medium circulating circuit 23.