PURPOSE: To enable automatic air-conditioning control only by changing software without using new sensors by estimating the radiation temperature on the basis of the outside air temperature and room temperature, and estimating air speed on the basis of blower voltage.

CONSTITUTION: A temperature setter 41 sets the room temperature of an air- conditioned room. A radiating temperature estimating means 100 estimates the radiation temperature on the basis of a room temperature sensor 31 and an outside air temperature sensor 32. A clothes quantity estimating means 200 estimates the quantity of clothes on the basis of the outside air temperature. An air speed estimating means 300 estimates air speed blasted into an air- conditioned room on the basis of blower voltage. A target room temperature computing means 400 computes the target temperature of the air-conditioned room on the basis of the estimated radiation temperature, clothes quantity and air speed. Air-conditioning is performed on the basis of this target temperature. Since the radiation temperature and air speed are not measured by sensors but estimated from the output of the existing sensors, comfortable air- conditioning control can be performed only by changing software.