To surely and stably fix a supporting shaft to a bobbin holder and prevent the damage of peripheral members of the bobbin holder having a structure to pass a supporting shaft having a bulged head at an end through both side walls of the bobbin holder and rotatably support a selvage yarn bobbin by the supporting shaft between both side walls.

A supporting shaft 5 has a bulged head 5a placed out of a side wall 1a and the other end 5b of the shaft is protruded through the other side wall 1b. A fastening nut 11 is screwed to the other end 5b. A fixing member 7 contacting with the inner surface of the other side wall 1b is placed between both side walls 1a, 1b in a state immovable relative to the supporting shaft 5. The side wall 1b of the bobbin holder is clamped between the fastening nut 11 and the fixing member 7 by fastening the fastening nut 11 and a fastening force is applied to the fixing member 7 by this process.