Abstract: A device for detecting the position of a physical defect on a buried pipe includes a leak-of-fluid signal detector, a number of vibration signal detectors, and a device body and can detect the position of a site of a leak, into the ground, of a fluid running through a fluid pipe buried beneath the ground surface. The device body calculates vibration amplitudes and speeds via associated vibration signal detectors with the use of the outputs of the respective vibration signal detectors, calculates cross-correlation functions of the vibration amplitudes and speeds with the use of the vibration amplitudes and speeds and the output of the leak-of-fluid signal detector, calculates the amplitude intensity for each cross-correlation function, and generates resultant vector data representing the position of the leak-of-fluid site with the use of the vibration intensity.