  We measured the radiation damage on silica aerogel \v Cerenkov radiators
originally developed for the $B$-factory experiment at KEK. Refractive index of
the aerogel samples ranged from 1.012 to 1.028. The samples were irradiated up
to 9.8~MRad of equivalent dose. Measurements of transmittance and refractive
index were carried out and these samples were found to be radiation hard.
Deteriorations in transparency and changes of refractive index were observed to
be less than 1.3\% and 0.001 at 90\% confidence level, respectively. Prospects
of using aerogels under high-radiation environment are discussed.
