An automotive air conditioner which conditions air making use of radiation of heat of a condenser and absorption of heat of an evaporator effectively. The evaporator 207 and the condenser 203 are disposed in a duct 100. A bypass passageway 150 is provided sidewardly of the condenser 203 in the duct 100, and a flow rate of air bypassing the condenser 203 is controlled by pivotal motion of an air mixing damper 154. Another bypass passage is provided sidewardly of the evaporator 207 in the duct 100, and a flow rate of air bypassing the evaporator 207 is controlled by pivotal motion of a bypass damper 159. Air is conditioned to an optimum blown out air temperature by varying the cooling rate at the evaporator 207 and the heating rate at the condenser 203 and is blown out to a room of an automobile from spit holes 141, 142 and 143. An outside heat exchanger is provided outside the duct 100, and a flow of refrigerant is changed over suitably among the outside heat exchanger 202, the evaporator 207 and the condenser 203 to perform cooling operation, heating operation, dehumidifying operation, dehumidifying heating operation and defrosting operation.