A method of non-destructive inspection of a subject body including an element is comprised of irradiating the subject body with a neutron ray through a first measurement point and a second measurement point; measuring an elapsed time after a first time point when a resonant neutron specific to the element passes through the first measurement point and before a second time point when a prompt gamma ray made emitted by the resonant neutron from the subject body is detected at the second measurement point; and determining a location of the element in the subject body by the first measurement point, the second measurement point, a relative position toward a surface of the subject body, and the elapsed time.