PURPOSE: To provide a control device of an air conditioner in which adhering of remaining water to fins of an outdoor heat exchanger upon completion of defrosting operation is eliminated, an amount of outdoor air is maintained, a frosting amount is reduced, a heating capability is improved, a heating time is extended and a complete defrosting is performed.

CONSTITUTION: A control device is comprised of a temperature sensing means 18 for sensing a temperature of an outdoor heat exchanger of an air conditioner and an outdoor controller 19 for receiving a temperature sensing signal 101 from the temperature sensing means 18 and controlling a compressor 11, a four-way valve 12 and an outdoor fan motor 17a. In the case that a temperature of the outdoor heat exchanger is less than a specified value during a heating operation, the heating operation is stopped and changed over to a defrosting operation. In the case that a temperature of the outdoor heat exchanger is more than a specified value, the heating operation is restarted. The outdoor control device 19 is provided with a control device for performing an operation of the outdoor fan motor 17a during a defrosting operation.