To absorb effects by backlash, expansion and contraction in a thrust direction of a control valve caused by an operational state or environmental variation, and to avoid increment in sliding resistance of a link part under the effect of components or assembling precision to enable a smooth open/close operation of a control valve in a link mechanism for an actuator and a control valve.

In a connection part of a control valve and an actuator for driving the control valve, the driving force of the actuator is transmitted to the control valve through a universal joint having a spherical shape.