Method and apparatus for non-destructive inspection of flaws in metal materials include exciting coils centered on a longitudinal axis of a cylindrical or columnar metallic material to be examined being arranged to surround the examinee material. A multiphase alternating current of such a relatively low frequency as to cause the exciting coils to generate a rotating magnetic field which rotates about the longitudinal axis of the examinee material is superimposed with a high frequency alternating current having an inspection frequency selected on the basis of the necessary sensitivity for detection of surface flaws of the examinee material. The composite multiphase current is applied to the exciting coils so that an electromagnetic effect induced in the surface of the examinee material by the high frequency alternating current is rotated for shifting circumferentially about the examinee material along with the rotating magnetic field. A detecting element group disposed in the proximity of the surface of the examined material detects the changing of the electromagnetic effect, dependent on the presence or absence of a surface flaw of the examinee material.