We have observed the incoherent nuclear resonant scattering (NRS) of synchrotron radiation from Fe-57 in hematite by changing the number of resonant nuclei while the other conditions remained unchanged. The experiments elucidated that the elastic part in the incoherent NRS is not proportional to the number of resonant nuclei, while the inelastic part is proportional to it. We could explain the dependence of the incoherent scattering in the energy spectra on the number of resonant nuclei by means of an attenuation effect. We discussed the possibility for the application of the incoherent elastic scattering to the study of the electronic-state changes accompanied by phase transitions for nuclides with high-energy excited states.