Anomalous Magnetism of UPT_{3}:

UPt${}_{3}$ exhibits a paradoxical behavior in its antiferromagnetism. Namely, the neutron scattering experiments surely detect the antifferomagnetic ordering below the transition temperature ${\rm T}_{N}\sim 5K$, while no trace of the transition is seen in the NMR experiments and in the specific heat at ${\rm T}_{N}$. For resolution of this paradox, we propose the ``SDW state'' which oscillates with a finite frequency larger than those of the NMR and smaller than those of the neutron scattering. For demonstrating such possibility we seek the divergent point of susceptibility, and offer a preliminary calculation of the frequency dependence of ``magnetization''.