A modularized externally-driven joint structure can be used for general purposes. An externally-driven joint structure: includes a shaft member that extends in an axial direction; and a number of rotatable members that are arranged along the axial direction, and are coupled with each other by the shaft member in an axially rotatable manner. Each of the rotatable members includes a pair of face portions that face each other in the axial direction, a side wall portion that is arranged along the outer circumferential edges of the pair of face portions, and at least one coupling portion that is arranged at the face portions or the side wall portion, and is coupled with a link member constituting a link of a robot.