Irradiations of the nanostructured silicon with Si+ and He+ ions were carried out with energies of 200 and 150 keV, respectively. Raman scattering showed destruction of the structure after irradiations and accumulation of defects at different fluences of irradiation. It is shown that monocrystalline silicon films are amorphized under irradiation at 0.7 displacement per atom. However, porous silicon does not completely amorphize at 0.5 displacement per atom, a weak signal is observed in the Raman spectra corresponding to the amorphous silicon phase, and at the same time there is an obvious signal from the crystalline phase of silicon. The size of nanocrystallites in the structure of porous silicon was estimated at different fluences of irradiation.