Abstract: A touch probe comprises an ultrasonic vibrating horn having a piezoelectric element which is sandwiched between electrodes and converts an RF electrical signal into ultrasonic vibration, and a feeler to be brought into contact with an object to be measured. The horn is ultrasonically vibrating in accordance with the ultrasonic vibration of said piezoelectric element. The probe further comprises a device for inputting an RF electrical signal between said electrodes so that the RF electrical signal substantially coincides with a mechanical natural frequency of said ultrasonic vibrating horn and a touch detecting device for monitoring a current between said electrodes to detect a touch between the object to be measured and said feeler in accordance with a change in current value produced at the moment said feeler touches the object to be measured.