PURPOSE: To improve stop position setting accuracy and shorten control time by connecting the pressure passage of an input shaft, rotatably fitted into a feedback shaft, to one of the oil passages of an actuator, and providing a throttle part, changed by relative rotation, between the other oil passage and a return passage.

CONSTITUTION: An input shaft 22 is rotatably fitted into a feedback shaft 21 connected to a rotary actuator R, and the feedback shaft 21 is provided with a first to a third ports 36-38 communicated with the oil passages a, b of the rotary actuator R and a tank. A connected opening area among a pressure passage 42 connected to either one of the first and second ports 36, 37 by the relative rotation between both shafts 21, 22, a return groove 44 for connecting the other port to the tank and the third port 38 is to be changed by relative rotation among them. Stop position setting accuracy is thereby improved, and control time can be shortened.