PURPOSE: To improve execution performance by suspending a parent child pipe through a jig equipped with a shift roll on a rail installed along a main girder and assembling a suspended scaffolding and successively pulling out the suspended scaffolding.

CONSTITUTION: A rail 25 is previously installed along a main girder 1, and a jig 14 having a shift roll in the upper part is suspended. Then, at a middle place of a bridge board 17, a parent child pipe 15 is suspended on the jig 14. A roller bridge 16, and a suspended scaffolding 20 which has a desired length and consists of a scaffolding plate 7, hardrail 8, net 9, etc., are assembled on the parent child pipe 15. Then, the scaffolding 20 is pulled out by a winch 21 installed on the other bridge board 17, and is successively shifted and installed at a desired position, and the bridge is inspected and repaired. Accordingly, the suspended scaffolding can be assembled and disassembled safely and efficiently, and further in a road part, the construction cost due to the traffic regulation can be economized.