Abstract: A method for evaluating atomic vacancies in a silicon wafer surface layer includes: element formation in which a pair of comb-shaped electrodes are formed on the same surface of a silicon sample over piezoelectric thin films; detection during which the sample is cooled and an ultrasonic pulse generated from one electrode while an external magnetic field is applied, the ultrasonic pulse being propagated through the sample surface and received by the other electrode, and a phase difference being detected between the ultrasonic pulse generated by the one electrode and the ultrasonic pulse received by the other electrode; and evaluation during which the sample surface elastic constant is determined on the basis of the phase difference, and the atomic vacancies in the sample surface are evaluated on the basis of changes in the elastic constant according to temperature or changes in the elastic constant according to the magnetic field intensity.