PURPOSE: To simply install a scaffold device at a necessary position by providing ridge hooking bodies suspendibly holding support frames on the ladder-shaped support frame and horizontally and removably providing lateral bars between holders provided on the support frames.

CONSTITUTION: Pairs of the right and left holders 4 are provided at a preset interval between a pair of the right and left lengthy separators 3 storably in the thickness width of the separators 3 to form support frames 2. Ridge hooking bodies 12 are provided at the upper end of the support frames 2. A pair of the right and left support frames 2 are suspendibly held on the roof flat side via the ridge hooking bodies 12, end lateral bars 19 are mounted on the holders 4 to form a scaffold device 1.