The spectral response changes of a silicon solar, cell damaged by γ-ray were measured. These changes suggest the decrease of minority carrier life time in the bulk, and the recombination centers introduced by the γ-ray irradiation. The calculated results of the spectral response are presented, which show the variation of response with minority carrier life time in the bulk region. Minority carrier life time in the bulk region were obtained by comparing experimental results with calculated curves. The densities of E-center in P/N-type cell were estimated with the minority carrier life times obtained in this way.