To nondestructively diagnose with high precision and in a simple and quantitative manner the surface deterioration, hardening, fatigue, or the change in liquid quality of various kinds of materials, with high accuracy in a nondestructive manner.

With a diagnostic measuring sensor for various kinds of materials, a transmitter 3 and a receiver 4 for transmitting and receiving ultrasonic waves formed of shear-horizontal wave of shear waves, are arranged in opposite positions in a sensor body 1a, and a piezoelectric body 5 is arranged between the transmitter 3 and the receiver 4 in contact with a specimen 2 through wedge members 6, 7. With a diagnosis device for various kinds of materials, pulse-receiver parts for controlling transmission and reception, are connected to the transmitter 3 and the receiver 4, and an A/D converter part for digital-converting the waves received from the receiver 4 side, and a calculating-processing CPU equipped with a display for displaying waveform are connected to the pulser-receiver parts. With diagnosis method, a part of ultrasonic wave propagated between the transmitter 3 and the receiver 4 leaks to the specimen 2 to be diffracted-propagated, and on the basis of the obtained waveform, the surface deterioration, hardening, fatigue, or the change in liquid quality, are measured.