A vehicle rear air conditioner includes an air conditioning case connected with a blower and having a face vent, a floor vent and a vent door for controlling opening and closing of the vents. An evaporator and a heater core are embedded in the air conditioning case and a temperature control door controls opening and closing of a cold and a hot air passageway. The rear air conditioner includes a passageway member in order to discharge part of air flowing through the cold air passageway or the hot air passageway toward one of the vents. The passageway member has an inlet for inducing the part of air and an outlet for discharging the part of air and the vent door includes at least one interference preventing part.