A magnetic body inspection apparatus includes a magnetic field application unit configured to apply a magnetic field to a long material including a magnetic body to be inspected, a detector configured to excite, in a longitudinal direction of the long material, magnetization of the magnetic body, the detector being configured to acquire a detection signal based on the magnetic field of the magnetic body that has been excited, and a detection apparatus body including the magnetic field application unit and the detector, the detection apparatus body being configured to be attachable to the long material in a short-side direction of the long material.