Abstract: The constitution comprises a grille for sucking air, a heat exchanger for exchanging heat with the air, a blower for feeding the air exchanged of heat by the heat exchanger, and an air diffuser for blowing out the wind generated by the blower. The air diffuser has such a shape that the direction of the wind blown out from both ends in a horizontal direction may be the lower direction than the direction of the wind blown out from the center in the horizontal direction. The air diffuser has such a shape that the outer circumference of the section in the horizontal direction has a nearly arc shape. It can be installed at a corner of mutually adjacent walls of a room or on a wall. In this constitution, the heat exchanged wind reaches uniformly all parts of the room, and the comfort is notably enhanced. At the same time, generation of unusual sound is suppressed.