PURPOSE: To improve an efficiency by a constitution wherein the amount of feeding fuel is controlled by the deviation of a temperature at the vicinity of the primary side of an indoor side heat exchanger with respect to a set value and the output torque of an internal-combustion engine, in the air conditioner equipped with a compressor driven by the internal-combustion engine.

CONSTITUTION: The set value of a room temperature setter 11, provided in a room to be air-conditioned, and a room temperature, measured by a room temperature sensitive element 8 provided at the primary side of the indoor side heat exchanger 5 and a linearize 13, are compared in a first active element 14, then, the difference is inputted into a second active element 16. On the other hand, the output torque of the engine, outputted by a F/V convertor 15 in accordance with the frequency of rotation outputted by a rotation sensor 3 for the internal-combustion engine, is inputted into the second active element 16 and added to the input of the temperature difference, then, is inputted into an output convertor 17. A fuel amount control valve 2 is controlled through an oscillating circuit 18 and a driver section 19 to adjust the revolving number of the engine. According to such constitution, the efficiency may be improved.