To provide an air conditioner of bidirectional ceiling cassette type capable of ensuring blowing-off of excellent cold air and warm air with operation of one wind direction button of a remote controller.

When an indoor unit is disposed in the vicinity of the center of a ceiling upon an air conditioner of bidirectional ceiling cassette type being installed on the ceiling, two flaps 8, 9 are changed over to a mode where they are brought into synchronization for swing operation, and an air direction is diffused to both sides at an angle θ and cold or warm air is blown out into a room (A). When the air conditioner is installed around the ceiling, the flap located around the ceiling, e.g. the flap 8 is changed over to a mode where the air direction is selected and fixed in a vertical direction while the flap 8 located on the side of a window and a wall has a vertical air direction whereby cold or warm air is blown out into the room and hence blowing of the cold or warm air to the window and wall can be avoided (B). Further, the flap 9 disposed on the side of the center of the ceiling swings to blow off cold or warm air into the room after it is diffused at the angle θ.