To provide an easily assembled frame structure body when a structure body, etc. are constructed, by positioning and supporting a member to be fastened at a protrusively bent portion of a pipe body and can surely hold the member to be fastened at the protrusively bent portion of the pipe body, by maintaining the strength of a pipe frame through reducing the cut-out portion from the pipe body even if the protrusively bent portion is formed on the pipe body.

The protrusively bent portion 19 is provided on part of the joint 17 of a square pipe 14 to be used as a frame. The protrusively bent portion 19 is formed on only one side of the ends butted against each other at the joint 17 so as to be perpendicular to the surface having the joint. The protrusively bent portion 19 can be easily bent because notched portions 19a are provided on both sides of the protrusively bent portion 19. A side plate 11 to be fastened to the square pipe 14 is provided with a hole 15 so as to correspond to the protrusively bent portion 19. The height of the protrusively bent portion 19 can be freely selected according to the thickness of the side plate 11, etc.