PURPOSE: To cool and dehumidify air in the ceiling, and to prevent the outer circumference of the main body of an air conditioner from forming condensed dew droplets caused by the continuous cooling operation of the same for a long period of time by providing inlet and outlet openings on the main body of the air conditioner embedded in the ceiling,

CONSTITUTION: In the case where the cooling operation of an air conditioner installed in the ceiling is carried out, indoor air is flowed into the air conditioner by a blower 28 through as inlet port 25 as indicated by the arrow E, guided into a heat exchanger 29 after passing through a filter 36, and blown into a room through an outlet port 26 as indicated by the arrow F after being converted into cold air by the heat exchanger 29, thus constituting a cooling air flow path. A part of air in the ceiling 23 is induced by the blower 28 through an inlet opening 35 and flows into an inlet flow path 39 on the way of the cooling air flow path. The air this induced is mixed with the air, which has been flowed in through the inlet port 25, in an inlet flow path 34, the mixed air passes through the heat exchanger 29, and the cooled air is blown into the room. In this instance, a part of cold air is blown into the ceiling 23 through an outlet opening 33 provided in an outlet flow path 40. According to this method, a temperature and humidity in the ceiling 23 are lowered, and a difference between a temperature in the room and a temperature in the ceiling 23 is reduced, thereby preventing condensation dew of droplets.