PURPOSE: To prevent cold air feeling of a person due to the lowering of blow- off temperature and appropriately adjust air flow quantity to elevate air-conditioning efficiency by periodically detectin the blow-off temperature and controlling the capacities of an indoor blower and a compressor.

CONSTITUTION: Set temperatures of a first set value T1 < a second set value T2 < a third set value T3 are provided in the blow-off temperature. The air conditioner comprises detection means for detecting the room temperature and detection means for detecting the blow-off temperature. In the case where the detected room temperature is within the range of the set temperature, when the blow- off temperature decreases and becomes lower than the first set value T1, the compressor frequency is lowered by a step. When the blow-off temperature rises up and exceeds the second set value T2, the frequency is controlled to be restored to the original state. Further, when the blow-off temperature exceeds the third set value T3 and the fourth set value T4, corrections are added to the indoor fan motor so that the rotational speed is raised by one step, and when the blow-off temperature is lowered, the rotational speed is lowered at a one step lower temperature, whereby the blow-off temperature is controlled to keep a value between the first set value T1 and the fourth set value T4.