PURPOSE: To promote a reduction in the number of part items, a simplification in structure, an improvement in the working property of installation and vice versa, and a reduction in cost.

CONSTITUTION: This is a steel form installer which attaches each lower part of both rising forms 30 to each top face 25A of a symmetrical pair of base forms 25, and it is composed of a connecting member 26 with each hole 28 conformed to each mounting hole 27 of the base forms 25 at both ends, two fastening plats 32 with each rising form engaged part 34 and mounting hole 33, and two mounting bolts 29 being inserted into the mounting holes 27 and 33 and screwed in tapped holes 28 of the connecting member 26. In addition, the base form 25, the connecting member 26 and the fastening plate 32 are all integrally clamped together by the mounting bolts 29.