PURPOSE: To constitute an actuator driving circuit without using any spool valve or a large unload relief valve.

CONSTITUTION: The driving circuit of an actuator is composed of two parallelly provided chick valves 42, 43 by which a valve unit 40 can be openly/closely operated, and opening/closing valves 44, 45 serially connected thereto and capable of mlaking two check funcctions for openly/closely operation. A hydraulic pump 21 is put in connection between the opening/closing valves 44 and 45, and a tank 22 is put in connection between the check valve 42 and 43. The oil chamber 12 of an actuator 1 is put in connection between the check valve 42 and the opening/closing valve 44 in serial thereto, and then the other oil chamber 13 of the actuator 1 is put in connection between the check valve 43 and the opening/closing valve 45 connected in serial thereto.