To provide a method and device for inspecting a product defect of a rolling device component capable of accurately inspecting whether there is a product defect in the rolling device component manufactured by insert molding without being accompanied by breakdown such as cutting.

The existence of the product defect is determined using the inspecting device comprising an exciting coil 16a for applying an alternating current magnetic field to the rolling device component in inspecting whether there is a product defect in the rolling device component manufactured by insert molding, an induction coil 16b for detecting variation of the magnetic flux density of the alternating current magnetic field applied from the exciting coil 16a to the rolling device component, an inductance variation detection circuit 17 for detecting the induced electromotive force occurring in the induction coil 16b, and a comparison determining circuit 18 for determining the existence of the product defect by comparing, with a threshold, the magnitude of the induced electromotive force detected by the inductance variation detection circuit 17.