In feather comforters and other comforters (primarily coverlet comforters) having a heat insulating material filled therein, to provide an air controlled comforter which makes it possible to obtain good sleep under comfortable sleeping conditions in terms of both temperature and humidity with the aid of warm or cool air, and which will not be moisturized itself so as to be free from the need of drying it each time after use. In a comforter in which a front cloth (1) and a rear cloth (2) is joined together at their peripheral edges to form a shape of bag, where a heat insulating material such as feather, wool, and cotton is filled in the bag, an air-permeable cloth (3) is joined with the rear cloth to define an air passage (4) ranging from hem to center part of the comforter. The air passage (4) is opened at the hem of the comforter, where an air opening (7) is provided for feeding warm or cool air. The warm or cool air fed through the opening to the air passage is passed through the sleeping space and the interior of the comforter with the heat insulating material filled therein, whereby a low-humidity, comfortable-temperature sleeping space is created while the comforter itself is dried.