To increase the connection holding force of a connecting body and to reduce the manufacturing cost of a stopper member.

The connecting bodies 1 and 2 with connection holes 11 and 21 for inserting a connection pin 3 respectively are rotatably connected with the common connection pin 3, and the stopper member 4 is stored for preventing the connection pin 3 inserted into the connection hole 11 of at least one connection body 1 from moving in the axial direction. The connection pin 3 has an annular lock groove 32 at least at one position in the axial direction. A board-like lock piece 43 to be elastically locked to the lock groove 32 of the connection pin 3 is attached to a cylindrical body part 42 of the stopper member 4 to be engaged with the connection pin 3.