ARTICULATION PART STRUCTURE OF ROBOT

PROBLEM TO BE SOLVED: To expand a rotation range of a robot arm, while preventing enlargement in the diametrical direction of an articulation part in a device having a hole part to be a wiring passage in the outer circumference of a shaft part. SOLUTION: A rotor 28 rotated by a servomotor and a speed reducer and having a second arm 14 (housing 31) attached thereto is provided in a front edge face of a third arm 15, and a circumferentially long hole part 33 for letting a wire 34 to pass through is formed in an end plate 23 provided in its outer circumference. A movable side first stopper 35 and a second stopper 36 are provided in both sides of the hole part 33 in such a state that the trajectories a and b are diametrically deviated. The housing 31 of the second arm 14 is provided with a fixing side first stopper 37, on which the movable side first stopper 35 abuts when clockwise rotating the third arm 15, and a fixing side second stopper 38, on which the movable side second stopper 36 abuts when counterclockwise rotating the third arm in positions deviated circumferentially. A frame 31 is provided with a constricted part 31a escaping from lapped with the hole 33. This constitution can enlarge the rotation range B.