PURPOSE: To make it possible to shut the window in spite of the presence of the air conditioner and to prevent the air conditioner from becoming an obstacle in the room when the air conditioner is not in use by a method wherein the fixing frame of the air conditioner is fixed to the outermost rising part of the window frame and the body for the air conditioner is made to extend outside the window.

CONSTITUTION: A sash 4 fixed to the window 3 of a house is provided with a drain rail 5, an inner rail 6, an outer rail 7 and a screen rail 8 in that order in the direction from the inside A to the outside B of the room. In case the air con ditioner is fixed to the window 3, the fixing frame 9 for fixing the body 11 of the air conditioner is fixed to the outermost rising part of the sash 4, that is, the screen rail 8 by means of screws 10 and the body 11 of the air conditioner is fixed to the fixing frame 9 by means of metal fittings 14 or the like in such a manner that the body 11 juts out from the window. In this case, the fixing frame 9 is formed of two sections 9a and 9b so that it can expand and contract in the vertical direction in proportion to the height of the window to which the body 11 of the air conditioner is fixed.