A linkage system which offers high rigidity and good assemblability and producibility, and enables parts such as rotary transmission components and actuators to be readily installed. A linkage system includes an input member disposed on an input side, an output member disposed on an output side, and three or more link mechanisms, each link mechanism consisting of end links rotatably coupled to the input member and the output member, respectively, a center link rotatably coupled to the end links on the input side and the output side, and four revolute joints by which the end links are rotatably coupled to the input and output members, and to the center link. The link mechanism being geometrically identical with respect to a center cross-sectional plane relative on the input and output sides. Each of the revolute joints of the link mechanism includes bearings that support at both ends of the revolute joint.