To provide a torque regulating nut having a simple structure applied to a winding fastening band metal fitting, capable of accurately and surely fastening by specified fastening torque, and confirming the completion- noncompletion of fastening at a glance.

A torque operation part 4 having a tool hooking surface 40 on the outside is integrally formed on a nut body 3 having a female screw hole 30. The torque operation part 4 forms a nontrue circular hole 41 concentric with the female screw hole 30 over the nut body 3 from an end surface, and larger than the diameter of the female screw hole 30. A rupture part 5 having a relatively large-small thicknesses 5a and 5b around the nontrue circular hole 41 is formed in the boundary of the nut body 3 and the torque operation part 4 via a constricted part 7.