A managing structure, for an umbilical member (6,60) for a work tool of a robot (10), capable of stabilizing the motion of the umbilical member during the operation of a wrist of the robot and making the work of modifying the system of the robot easier. The umbilical member is introduced into an opening (26) formed at the back of a base (14) of a forearm. The umbilical member extends through a hollow portion of a speed reducer (30) and is drawn from a first opening (21) formed on the side of a first wrist element (15). A cable (62) for welding current and a tube (63) for supplying shield gas, constituting the umbilical member, are directly connected to a welding torch (19) rotatable about a third axis (C). A welding wire (61) is guided and fed by a feed roller (51) of a wire feeder (50) and, then, is connected to the welding torch (19) with the cable (62) and the tube (63). The feed roller (51) is driven by a motor (52) contained within the first wrist element (15).