To provide a hydraulic actuator drive circuit provided with a damping mechanism of high reliability relating to trouble and mixing of air.

In a servo valve 63 of an electrohydraulic servo valve 61 controlling an actuator 62, in accordance with a control signal, a pressure difference between first/second oil chambers 68, 70 is controlled, a spool 66 is displaced, hydraulic oil supplied from a pressure supply port 64 is supplied to a cylinder 73 of the actuator 62, and hydraulic oil discharged by the cylinder 73 is collected to be discharged from a discharge port 71. A pressure difference of the cylinder 73 is detected by a pressure detector 93, a pressure feedback device 94 interlocked with a detection piston 96 of this pressure detector 93 is interlocked therewith, a pressure difference between the first/second oil chambers 68, 70 of the servo valve 63 is reduced, and a damping effect is given to the actuator 62.