A sensor device for acquiring at least one rotational property of a rotating element, particularly a rotational speed of a compressor wheel of an exhaust-gas turbocharger, includes at least one magnetic field generator for generating a magnetic field at the location of the rotating element, at least one magnetic sensor, e.g., a coil, for acquiring a magnetic field generated by eddy currents of the rotating element, and at least one pole pin. The pole pin is elongated at its end facing the rotating element and includes a section that is not enclosed by the magnetic sensor. The sensor can be installed as a plug sensor in a blind-end bore in the housing of the exhaust-gas turbocharger.