PURPOSE: To reduce the thickness of an attachment and make it versatile by integratedly forming a cushioning member made of a thin soft resin layer inside a double layer glass holding frame, and detachably arranging a bead on a supporting leg for inserting to support the holding frame with the sash groove.

CONSTITUTION: A cushioning member 25 made of a thin soft resin layer 26 is integratedly formed on the inside of the side wall 14 of a holding frame 12, and the width of a groove 15 is made small. Next a bead 31 is selected so as to conform to the width of the glass groove of a sash, fed to a supporting leg 17 for inserting from the end face side, and the projecting parts 33, 34 are respectively locked with a locking groove 18a and a projecting part 22 so as to be detachably fitted. Next, one side edge part of a double layer glass is introduced to the cushioning member side. If necessary, soft tongue pieces 27 are provided on the cushioning member 25 so as to insure watertightness. The supporting leg 17 with the bead member 31 fitted thereto is press-fitted in the glass groove of the sash until a wing-like supporting arm part 32 is placed on the sash face. Hence the groove width can be made small, and an attachment main body can be used in common by selectingly using the bead.