PURPOSE: To enable cable laying while all of the cable fixing part is attached to an arm body by rotating a cable clamping plate around a fixing member and then releasing or closing a cable receiving groove with rotation of this cable clamping plate.

CONSTITUTION: Since the cable clamping plate 3 is rotatable around a cable fixing member 4, the cable clamping plate 3 call be moved to the position where the cable receiving groove 23 is released and to the position where the groove 23 is closed. Therefore, while the cable fixing members 4 such as a bolt 41, a nut 42, a washer 43 are attached to the arm body 1, a cable 3 may be loaded and unloaded at the position where the cable receiving groove 23 is released, and the cable 5 is fixed at the position where the cable receiving groove 23 is closed. Thereby, the laying of cable 4 can be conducted, while all of the cable fixing members 4 are fixed to the arm body 1.