Abstract: A vehicle air-conditioning device with a rear air-conditioning unit does not having a temperature control device, yet prevents excessive hot air blow temperatures when the fan blow is low. A heat exchanger for heating the air blow from the blower is installed in the case of the air-conditioning unit at the rear of a dual air-conditioning type vehicle air-conditioning device along with a cooling air bypass path to allow cool air to bypass the heat exchanger. A cool air bypass door is installed in the cool air bypass path to open and close it as needed. When the blower is set in low speed mode and hot air heated by the heat exchanger is blown out from the blow path in foot mode, the cool air bypass door is set to a position to open the cool air bypass path in a process that mixes cool air and warm air in the blow path and lowers the temperature of the hot air.