Abstract: A pair of hydraulic cylinders 10 which are coupled to a driven member, placed parallel to each other and extend/contract in synchronization with each other, and a control valve 20 which controls hydraulic fluid supplied to or discharged from the hydraulic cylinder 10 are provided. An elastic support mechanism 50 which supports the control valve 20 to each hydraulic cylinder between the paired hydraulic cylinders 10; metallic piping 30 and the metallic piping 40 which connect the control valve 20 with the respective hydraulic cylinders 10 and leads the hydraulic fluid controlled by the controlling valve 20; and curved portions 31c, 32, 41c, 42a which are provided at some midpoints of the piping and flexibly deform in accordance with relative deformation of each hydraulic cylinder 10 are provided. A difference in relative displacement of each hydraulic cylinder with respect to the control valve 20 is absorbed by deformation produced in the elastic support mechanism 50 and the curved portions.