PURPOSE: To improve piping workability upon installation by providing a support tool including a folded hook on a back plate, the hook being brought down on this side upon working while being stood and accommodated upon non- working, and further providing a stopper portion where the folded hook is engaged with an indoor unit.

CONSTITUTION: An indoor unit body 3 hung on the upper end of a fixed back plate 2 is properly angularly slanted around a reception groove in the upper edge end as a fulcrum so as to be opened on this side in its lower portion whereby a piping work gap A is formed at the bottom thereof. For keeping the gap A, a slanted support tool 7 stood and accommodated on the surface of the back plate 2 is brought down on this side around a lower end pivot portion as a fulcrum against gripping between a stopper piece 9 and a longitudinal stopper piece 11. Thereupon, as a folded hook portion 6 formed out the tip end of the slanted support tool 7 is faced to a lower U-shaped slanted fixed portion 12 of the pivoted indoor unit body 3 so as to be inserted into the slanted fixed portion 12, the folded hook portion 6 stops at a frame corner 12b becoming an inclination end, and a stopper pawl 13 is fitted in a stopper hole 8 provided at the root of the folded hook portion 6 to ensure pawl engagement.