PURPOSE: To simplify and miniaturize the shape of articulated parts by making the rotating shafts of motors, which drive the arms of motors, concentrically with each other and providing the robot structure such that the torque is transferred to each corresponding arm, penetrating the inside of other arms.

CONSTITUTION: Motors 10W12, which give power to the tips of arms 1, 2, are arranged at the base part 13 in such a manner that they are placed along a common rotating center axis. Rotating shafts 10aW12a of these motors 10W12 are arranged in concentric structure. On the other hand, the torque of the motors 10W12 is transferred to the tips of the corresponding arms 1, 2 by means of 2 power transmitting mechanism, which is connected to the rotating shafts 10aW12a, and which penetrates the inside of arms 1 and 2, thereby operating the arms 1 and 2. If the motors 10W12 are arranged in the base part like this, all that should be done is only to arrange power transmitting mechanism parts like a gear or the like to articulated parts 4 and 6. The articulated parts 4 and 6, thus, can be simplified and miniaturized.