A plurality of tandem actuators including piston rods in each of which two pistons are provided in series are disposed in parallel. A rod end portion couples the piston rods of the plurality of tandem actuators on the outside of case portions and can be rotatably linked to a control surface. For each of the tandem actuators, first hydraulic chambers on the side opposite to the rod end portion side are in communication with each other in the two piston movement areas, respectively, and second hydraulic chambers on the rod end portion side are in communication with each other in the two pistons areas, respectively.