SYSTEM FOR CONTROLLING VALVE OPENING/CLOSING TIMING

A system for controlling valve opening/closing timing that allows an unlocking operation to be reliably performed is configured. When extracting a lock member from a recess, a second control valve is set to an unlock position, a first control valve is set to a predetermined position, and a relative rotation phase is displaced. As a result, the relative rotation phase is displaced in a direction opposite to the direction of displacement by cam average torque from a camshaft. Afterward, by setting the first control valve to a neutral position, the relative rotation phase is displaced by the cam average torque, and when this displacement occurs, a state in which the lock member is separated from an inner wall of the recess is created, thus facilitating extraction of the lock member from the recess.