AbstractThis paper describes dynamic behavior of non-ferromagnetic and ferromagnetic plates, and a non-ferromagnetic cylinder under strong magnetic field. The dynamic behavior of a ferromagnetic cantilevered plate, which is set along the uniform magnetic field, shows that its natural frequency increases with external magnetic induction. This means that a magnetic stiffness effect occurs in a ferromagnetic plate due to magnetization. The behaviors of non-ferromagnetic and ferromagnetic plates show that the magnetic viscous damping effect becomes larger almost proportionally with the squared external magnetic induction. A non-ferromagnetic cylinder also shows the magnetic viscous damping effect in a strong magnetic field. It is necessary to consider these magnetic stiffness and viscous damping effects for the structural design of a magnetic fusion reactor.