To solve the problem that a conventional technology depends on crack detection and the destructive analysis evaluation of a crack occurring due to fatigue damage, cannot grasp a degree of the fatigue damage until the end of life in which the crack occurs; the whole structural member is needed to be universally and precisely searched in order to obtain efficient prediction result since the precision of life prediction largely depends on the detection oversight of the microcrack and the precision of the measurement of crack size; and the cost is expensive in spite of a low rate of the effect to the cost.

Ultrasonic spectroscopy measurement is performed concerning the structural member of secular use aiming at fatigue damage evaluation, and various amounts in regard to transposition occurring due to fatigue damage in the structural member of the secular use are calculated by using the measured results. The degree of the fatigue damage of the structural member of the secular use is quantitatively evaluated by using the correlation of the calculated values, the previously corrected fatigue damage and the various amount related to the transposition to judge the remaining life.