To provide a fall-prevention device for a scaffolding board preventing fall of a construction material or the like from the scaffolding board.

The fall-prevention device 15 made of metal mainly comprises a fall-prevention board 16 erected on the scaffolding board 11, a supporting part 17 extended downward from the fall-prevention board 16, and an engaging body 18 mounted to the lower end of the supporting part 17 to move up and down. Each insertion cylindrical part 17a is joined to the lower end of the supporting part 17, and a supporting shaft 19 is inserted into each cylindrical insertion part 17a. The engaging body 18 is mounted to the upper end of each supporting shaft 19, and each engaging body 18 is constantly urged upward by a spring force of a coil spring 21. An engaging part 16a of the fall-prevention board 16 is engaged with an engaging recess portion 14 recessed in the scaffolding board 11, and by engaging the engaging body 18 with the lower end of the scaffolding board 11, the fall-prevention board 16 is erected on the surface of the scaffolding board 11.