PURPOSE: To effectively prevent a stair type temporary ladder from swinging by using a simple, easy-to-install structure.

CONSTITUTION: A brace member 7 which comprises two rod members 8, 8 crossing and rotatably connected to each other at their middle portions is disposed between each of the pairs of upper and lower adjoining scaffold boards 1. Each of the scaffold boards 1 is freely detachably connected to the brace member 7 by engagement of a projecting shaft 12 secured to the side edge portion of each scaffold board 1 with mounting portions 11 which are formed at both ends of each rod member 8, 8 constituting the brace member 7 and each have a through hole 10 for the projecting shaft 12. The projecting shaft 12 is provided with a locking means 13 to prevent the mounting portions 11 engaged with the projecting shaft 12 from disengaging. Shoring members 19 for preventing the temporary ladder from swinging are laid between the temporary ladder and the vertical plane W of the working site and removably held in place.