A vehicle air-conditioning device includes a compressor, a heating unit, an outside air heat exchanger, a wind speed regulation unit, and a controller. The heating unit includes a heating heat exchanger and heats ventilation air supplied to a space to be air conditioned using a high-pressure refrigerant as a heat source. The wind speed regulation unit regulates a wind speed of air supplied to the outside air heat exchanger. The control unit performs, as a defrosting operation of defrosting the outside air heat exchanger, a dry defrosting mode for evaporating and removing frost adhering to the outside air heat exchanger in a state where the outside air is at a low temperature. In the dry defrosting mode, the controller causes the wind speed regulation unit to supply air to the outside air heat exchanger at a wind speed in a range determined to promote evaporation and removal of frost.