To provide a connecting tool having looseness resistant screwed structure of a connecting pin, excellent in a practical use and superior mass productivity, and also epoch-making.

In the connecting tool in which through-type installing holes 2A at an opposed tip portion of an U-shaped metal fitting body 1 are provided and a connecting pin 3 is provided in a bridged state by inserting and screwing up the connecting pin 3 from one of the installing holes 2A to the other of the connecting hole 2A, an projected portion 6 is arranged in an outside portion 5 of a hole-edge periphery of the one of the installing holes 2a which becomes a reference end side of the connecting pin 3. Then, projected to the inside of a hole-edge of the installing hole 2A by crushing the projected portion 6 by means of knocking or pushed pressure so that the connecting pin 3 or a looseness resistant pin 4 are formed to prevent from slipping out the projected portion 6 is deformed and.