PURPOSE: To prevent the occurrence of the slack, draw up, and sagging of an air hose, a control signal line, and a current collecting cable for weld, which are positioned in the vicinity of the wrist of a robot.

CONSTITUTION: A rotary joint mechanism 14 is provided for comprising a joint rotary body 12 rotated following movement of an output drive part 10 for a wrist and provided at a tip part with an attaching mount 8 for a cylinder, and a joint fixing body 13 which surrounds a part of the outer periphery of the joint rotary body 12 and integrally mounted on an output fixing part 9 for a wrist. The joint fixing body 13 is provided with an air intake port 20 to introduce air for working, a signal line lead-in port 21 through which an electric wiring 3 for transmitting a control signal is introduced, and a cable mounting part 22 to which a current collecting cable 4 for weld. Even when a wrist is widely rotated, interference of an air hose 2, protruded from the joint rotary body 12, with a peripheral device and contact of them with each other are prevented from occurring and receiving of a weld heat and spatter is reduced as low as possible.