PURPOSE: To make a horizontal correction without being hindered by an installed element by connecting the upper leg upper end of a wall fixed installed rail engagedly to a cutout of a fixture element in the state of supporting a space holding device in contact with the contact installed faces of the wall fixed rail.

CONSTITUTION: A leg part 3 of a fixture has a recess 20 opened toward the leg part end side. The shape of this recess 20 is so dimensioned that the inner slope width of the recess 20 at each leg part end is smaller than the whole width of a wall fixed installed rail 12, and the plane of a recess bottom part 21 at the upper flank 22 of the recess 20 is provided with a cutout 23 corresponding to the size of material wall thickness of the wall fixed installed rail 12, taking account of the inclined motion of a fixture element. The upper leg part end 15 of the wall fixed installed rail 12 is engagedly connected to the cutout 23 in the state of supporting the recess bottom part 21 and consequently a space holding device in contact with contact installed faces 15, 16 of the wall fixed installed rail 12.