A tool holding articulated arm 1 has articulations 4 each holding a ball 6 between a presser 11 and a front opening 8 of a housing 7. With small acting force of the presser 11, a strong fixing force is obtained at each articulation 4. The presser 11 has a cup shape whose circumferential edge e comes into linear contact with the surface of the ball 6 to exert a strong holding force on the surface of the ball 6.
