This air conditioning device for a vehicle comprises: a refrigeration cycle having a compressor, a condenser, an expansion valve, and an evaporator through which refrigerant sequentially flows; a high-temperature heat medium circuit in which a high-temperature heat medium that has been heat-exchanged with the refrigerant in the condenser circulates; a low-temperature heat medium circuit in which a low-temperature heat medium that has been heat-exchanged with the refrigerant in the evaporator circulates; a connection line for connecting the high-temperature heat medium circuit and the low-temperature heat medium circuit; a plurality of heat exchangers outside the vehicle that allow introduction of the heat medium; and a switching unit capable of switching modes for each of the plurality of heat exchangers outside the vehicle, among a mode for connecting to the high-temperature heat medium circuit, a mode for connecting to the low-temperature heat medium circuit, and a mode for not connecting to either of the high-temperature heat medium circuit and the low-temperature heat medium circuit.