A method and a device for measuring the rotational speed of a turbocompressor, in particular a turbocharger of a motor vehicle. A frequency of pressure pulses generated in the medium the blades or by the shaft of the turbocompressor is measured using high-frequency signal portion of a pressure sensor, and the turbocompressor rotational speed is ascertained from the measured pressure pulse frequency. Furthermore, the charge pressure of the turbocompressor can be ascertained from the low-frequency signal of the pressure sensor so that a single sensor is sufficient for both measurements. The pressure sensor can be arranged in the intake system downstream of the compressor, upstream or downstream of an intercooler.