To provide an assembling method for an iron reinforcing bar having a hoop line by which the assembling accuracy for the iron reinforcing bar can be improved, and even in a case where a main line and a hooped line are aggregated densely, a fastening operation is made easy and, the operation time on a scaffold can be shortened.

This method comprises a process for forming a hoop line aggregated element 12 by building up a given number of hoop lines, a guide means 24 installation process for holding the hoop line aggregated element 12 at the hoop line aggregated element fastening position or at the down side thereof, a process for making the guide means 24 hold the hoop line aggregated element 12, a process for installing the main line 11 at a given position, a process for fastening the hoop line aggregated element 12 to the hoop line aggregated element fastening position of the main line 11 and a process for removing the guide means 24.