To extensively increase and decrease a rotating area of each arm by respectively connecting the arms to a pair of ring type rotors of a concentric axial type motor.

This DD robot 100 by a concentric axial motor 20 is constituted by connecting first and second arms 5, 6 to each of ring rotors 35, 38 of the concentric axial motor 20, connecting third and fourth arms 8, 10 to each of the arms 5, 6 through each of axially supporting parts 7, 9 and to freely move a member 12 provided on a third axially supporting part 11 on a front end of each of the arms 8, 10.