PURPOSE: To simplify adjustment work by setting a jig for leveling at a specified position of a footing part as well as supporting a large sleeper by way of fixing a bundle hardware previously set in height on the footing part of a bundle base.

CONSTITUTION: Only a footing part 21 is formed at a specified position on the inside surrounded by a cloth base, an anchor bolt 24 is fixed on the upper face of this footing part 21 through a base plate 23 and a bundle hardware 22 is screwed and installed. Thereafter, a reception plate 30 is provided on this bundle hardware 22, a large sleeper 26 is placed on it and supported, and a jig 1 for leveling is installed along the side part of the bundle hardware 22. Thereafter, when the lower face of the large sleeper 26 reaches the upper face of the jig 1 for leveling, a cylindrical hardware 5 of the jig 1 is lowered downward and engaged with a columnar hardware 2 by an engagement system 7, and the large sleeper 26 is fixed in a set level state. Consequently, it is possible to improve workability of level adjustment extensively.