PURPOSE: To erect inclinatorily four legs of a steel tower inward at four corners of a square, to use a support pipe to bear a falling direction until the legs are anchored and to make it possible to adjust a mounting position, mounting direction and length of the support pipe.

CONSTITUTION: A square nut 5 is screwed to a screw shaft 4 borne on opposite tables 2 on the base, both leg sides of a U-shaped metal fixture 7 are pivoted on front and rear sides of the nut, and the lower end of a support pipe S is locked to the base of the U-shaped metal fixture 7. The upper end of the support pipe is fixed to legs of a steel tower. The support pipe S is so constituted that two pipes having respectively a small diameter and a large diameter are combined and that the length thereof is capable of adjusting.