The unit attaching device of the present invention has suspension brackets that have a hole for passing a suspension bolt suspended from a ceiling and that are installed to an indoor unit that is a unit to be suspended. The suspension brackets are installed on the ceiling side of the side surface of a housing of the indoor unit. For example, when an earthquake or the like occurs, the distance between a part that is the base point of the swing of the suspension bolt and the installation position of the unit can be reduced.