A metallic contaminant detecting method and apparatus according to the present invention detect metallic contaminants mixed in objects under inspection, such as food products, pharmaceuticals, and materials for industrial use, which are wrapped in electrically conductive packaging materials, e.g. aluminum. A small magnetic field is generated by applying a voltage to coils (10, 11) or supplying an electric current to the coils. A detection magnetic field generated from a metallic contaminant in response to the small magnetic field is detected as a detection voltage or a detection current of the coils (10, 11), and a detection signal is output. The detection signal is analyzed to detect the metallic contaminant. The small magnetic field is created by applying a small voltage or supplying a small electric current to the coils (10, 11) and using a non-linear portion of the magnetic field characteristics of cores constituting the coils (10, 11).