To provide an electrical hydraulic servo actuator with redundancy suitable for fail safe.

In a redundant control system, a logic crossing coupling is arranged between independent servo actuators 101A and 101B that have hydraulic actuators 106A and 106B, respectively. Logic valve devices 103A, 103B, 104A, 104B, 105A, 105B are connected to the hydraulic actuators 106A, 106B and control valves 102A, 102B. A hydraulic pressure input signal and an electrical input signal are inputted to the devices 103A, 103B, 104A, 104B, 105A, 105B. The redundant control system is suitably operational in a mode that the hydraulic actuators 106A, 106B operate or freely operate in response to or unrelated to a control signal, or in a mode that movement of a load controlled as a function of a hydraulic signal and an electrical signal inputted to the logic valve devices 103A, 103B, 104A, 104B, 105A, 105B unrelated to the control signal and is constructed such that the logic valve devices 103A, 103B, 104A, 104B, 105A, 105B generate hydraulic pressure output signals that become input signals of other actuators.