A motor-driven proportional fluid flow control valve has a linear motor including a slide valve body slidably mounted on a hollow iron core and an electromagnetic coil wound around the iron core. After a drive circuit has been energized, a constant current is passed through the electromagnetic coil to keep the slide valve body spaced from a stop surface while cutting off fluid communication between an inlet port and an outlet port. With the slide valve body out of contact with the stop surface, the slide valve does not produce noise which would otherwise be given off due to a fluctuating current flowing, through or vibrations of, the electromagnetic coil.