This magnetic body management system (100) includes: a first magnetic body inspection device (1) configured to acquire a detection signal (DS) before the magnetic body (MM) is installed at a location of use; a second magnetic body inspection device (2) configured to acquire a detection signal (DS) after the magnetic body (MM) has been installed at the location of use, the second magnetic body inspection device (2) having the same method as that of the first magnetic body inspection device (1); a server (3); a first transmission unit (4); and a second transmission unit (5). The server (3) is configured to estimate a deterioration state of the magnetic body (MM) based on at least the first magnetic body information (10) and the second magnetic body information (11).