To provide an integrity evaluation system of a structure for evaluating the integrity or the damage degree of the structure by adding an evaluation index of relatively high accuracy, regardless of the frequency, and to provide an integrity evaluation method.

The integrity evaluation method of the structure is constituted so as to evaluate the integrity or the damage degree of the structure, by pasting piezoelectric elements to the respective necessary parts of the structure and applying voltage to the respective piezoelectric elements to continuously observe the change in the piezoelectric impedances produced in the respective piezoelectric elements, while generating high-frequency elastic waves in the structure, and includes a step for forming a frequency-to-impedance waveform with respect to the respective piezoelectric elements, and a step for using either one of the integrity and the damage degree calculated from the respective evaluation indexes of the waveform shift quantity ΔS derived from the frequency-to-impedance waveform, waveform amplitude change quantity , waveform center-of-gravity change quantity ΔH and amount of change in frequency center-of gravity ΔG or an arbitrary combination of them.