PURPOSE: To distinguish the feature of the surface of a metallic piece by means of a coil sensor where output can be changed by the unevenness of the surface of the metallic piece by providing a metallic piece identification device in such a way that it faces the surface of the metallic piece passing a metallic piece path, making the device to be sufficiently smaller than the diameter of the metallic piece and providing the device on the surface of a passage wall so that almost the center part of the metallic piece can pass through a sensor part.

CONSTITUTION: (B) shows a sensor waveform W1 and a metallic piece section in the passage route RT1 of the sensor 4 against the metallic piece. (C) shows a sensor waveform and the metallic piece section in a passage route RT. When an edge 1a is uniform even if the passage routes differ, waveform values Vp1 and Vp2 corresponding to the edge are equal and Vp1=Vp2. Then, waveforms Vc corresponding to the center part 1c are mutually equal. When Vp1+Vp2>2Vc, for example, the center part is discriminated as dent against the edge. When the ravines of Vv1 and Vv2 exist and Vp1+Vp2≤2Vc, a projecting part is discriminated to exist in the center part.