To prevent unwanted oscillation control of a solenoid actuator so as to improve durability by detecting rotating speed of an internal combustion engine and inputting a signal obtained by processing an operating angle signal of a control shaft into control means, as well as reducing an output gain of a frequency belt according to the frequency of a detected speed of rotation.
An operating angle of a control shaft 16 is detected by an operating angle sensor 102 such as a potentiometer, the detected operating angle and a target operating angle are compared with each other by a control unit CPU. A signal for controlling the drive of a solenoid actuator 101, such as a DC servomotor, is feed back-controlled so as to set the operating angle of the control shaft 16 as the target operating angle. At this time, in the CPU, two band elimination filters BEF1, BEF2 for reducing the output gain of a frequency belt according to the frequency of engine rotating speed is mounted, for eliminating an operating angle fluctuation signal component of the control shaft 16 caused b torque fluctuation due to the rotation of a cam shaft, from a signal detected by the operating angle sensor 102.
