[en] Change of molecular weight of cardo polymer, new high-performance polymer, by γ-ray irradiation and the effect of conditions of ion irradiation on the damage distribution of polymer were studied. With SEC/MALLS measurement, cut conditions of molecular chain of polymer by γ-ray irradiation made clear by change of molecular weight and molecular weight distribution of cardo polymer and polystyrene standard sample. G(S) value ( productivity of cutting of molecular chain) of cardo polymer was larger than PS standard polymer. That is, molecular chain of cardo polymer was much easy to cut by γ-ray than PS standard sample. On polycarbonate irradiated by ion, the factors affected on damage formation and change of damage distribution by irradiation conditions were studied. Samples were 200 μm thick of polycarbonate irradiated by ions such as C⁺, B⁺, P⁺, Si⁺, Cu⁺ and Au⁺. When the sample was irradiated by 1 x 10²ⁱons/cm² to 1 x 10¹¹ions/cm² of the above-described ions, S parameter at 2.2 keV was affected largely by the electron energy deposition (keV/nm³). But, S parameter is the ratio of count number of center part to count number of whole part of annihilation γ-ray. The deposition process of electronic energy of irradiation ions affected on the damage of polycarbonate depend on ion irradiation. (S.Y.)