Radiation stability of the nanoporous silicon under gamma irradiation was investigated. Changes in the properties of porous silicon under gamma irradiation were registered by measurements of photoluminescence spectra and Fourier-transform infrared (FTIR) spectroscopy. Besides the appearance of point defects and their subsequent oxidation, the significant differences were shown to be in the behavior of the porous silicon properties in comparison with that of bulk silicon apparently due to the quantum size nature of nanoporous silicon.