To surely prevent the generation of the so-called buckling caused by rising of a pipe from a bending regulating member for pressing the pipe when the pipe is bent.

This member is the bending regulating member for benders which has a groove curved at a prescribed angle for bending the pipe P and with which the condition of bending of the pipe P is regulated by being pressed against the fixed pipe P. An attaching part 5 for attaching the auxiliary holding tool for preventing the buckling by pressing the pipe P opposing to the bending regulating member 2 when the pipe P is bent is provided.