To provide an anchor capable of giving strength to the anchor to prevent a collapse of soil although the conventional anchor could not completely prevent the collapse of soil because it was so simply constituted that a thin round steel was only put in a rod-like mortar.

Since a square pipe (or a twisted square pipe) perforating through all sides is used instead of the thin round steel, the mortar and the square pipe (or the twisted square pipe) are strongly connected with each other to increase strength of the rod-like mortar so that the collapse of soil can be prevented.