PURPOSE: To increase a possible adjustment quantity by connecting a roof finishing material on an inner side part of a side part connecting member, connecting a verge member on an outer side part, connecting a water-proofing plate between inner side walls, and adjusting the width by moving these along a beam.

CONSTITUTION: A natural lighting glass frame 2 and a water-proofing plate 41 are connected in parallel through a middle connecting material and a side part connecting material 1'. If the roof board width is smaller than a standard, the top end of a vertical bar 38 of the frame 2 is got closer to a standing wall 16, and the lower end is got closer to an inner wall of a roof finishing material supporting groove 22. A standing wall 42 of the water-proofing plate 41 is inserted in a space 40 between water-proofing plate containing chambers to be close to the center line of the connecting material 1', where all the connections and combinations are achieved by minus installation by installing, combining and connecting them at positions inside adjusting parts. In case the roof board width is larger than the standard, the top end of the vertical bar 38 is got closer to a suspended member 34, and the lower end is got closer to an outer wall of the supporting groove 22, and the standing wall 42 is got closer to a side wall of the supporting groove 22 for plus installation.