Abstract: The surface of the member to be inspected is covered with powder deposited by using, for example, static electricity prior to the flaw detection. The member surface is covered so as to be partly exposed by setting the average thickness of the powder layer to 0.1D-0.6D, where D is the average particle diameter of the powder, under an assumption that the powder particles in the powder layer are virtually leveled into a uniform thickness film. Subsequently, the surface region of the member is heated by high frequency induction heating, and then the temperature distribution on the surface is measured with a radiation thermometer. The part for which the temperature measured is different from the surroundings is judged as a flaw. The surface of the member is covered with the powder so that the surface emissivity becomes almost uniform, and the resulting temperature distribution measured with the radiation thermometer becomes almost equal to the real one.