An injector, for injecting a fuel fluid into an intake manifold or into a combustion chamber of a cylinder of an internal combustion engine, includes an electromagnetic actuator that includes a magnetic circuit. The magnetic circuit includes a solenoid, an internal pole, and a magnet armature that cooperates with the solenoid and the internal pole, and is configured to generate a controlled force action between the internal pole and the magnet armature when the electromagnetic actuator is activated with the aid of an activating current and/or an activating voltage. The injector includes a gap in the area between the internal pole and the magnet armature, and includes a valve sleeve that has either paramagnetic material properties in and outside the area of the gap or paramagnetic material properties in the area of the gap and ferromagnetic material properties outside of this area.