The invention relates to a system for measuring vibration on a machine, with a carrier (14) for placing onto a measuring point (12) of the machine, a sensor (16) arranged on the carrier for detecting vibrations, an arrangement (16, 22, 28, 30) for detecting the electromechanical impedance of the sensor and also a monitoring device (22, 24, 26) for monitoring the current coupling of the carrier at the measuring point by means of evaluating the detected electromechanical impedance. The current coupling is in this case determined from the difference between the currently detected electromechanical impedance and the electromechanical impedance detected for a prescribed optimum coupling of the carrier to the measuring point.