PURPOSE: To provide excellent response characteristic even in the case where control deviation is small and a required flow rate is also small by deciding the number of servo valves driven corresponding to the flow rate.

CONSTITUTION: A servo valve control device has an operation means 1 to compute difference value between the value of target flow rate and the value of present flow rate; comparing means 2, 3 to compare the difference value with a fixed value; and changing over means 5 to 10 for the number of servo valves which set up the number of servo valves 17 to 19 driven corresponding to the difference value by a signal sent from the comparing means 1, and moreover control each servo valve so that the sum of flow rates controlled by the servo valves may agree with the difference value.