exciting coil 34 is wound around the support skeleton and two me sensing units 32 a and 32 b are placed inside of the support skeleton 33 the number of the me sensing unit may be one or more the me sensing unit may be installed interior or exterior of the support skeleton the support skeleton may be an integral body or an assembled body of more than pieces for the purposes of convenient production process and installation process the exciting coil may be one coil or more coils connected in series or parallel and the signal source of the exciting coil may be an ac signal or pulse signal fig4 a 4b and 4c are longitudinal sectional diagrams for a second exemplary structure of the stress monitoring device of fig2 the magnetic field generating unit is a permanent magnet 43 which forms a magnetic field loop together with the monitored component 41 via a yoke 42 the number of the permanent magnet 43 may be one 43 see fig4 a two 43 a 43 b see fig4 b three 43 a 43 b 43 c see fig4 c or more fig5 a 5b and 5c are longitudinal sectional diagrams for a third exemplary structure of the stress monitoring device of fig2 the magnetic field generating unit is the combination of.