[en] Macro-porous cation exchange resin Dianion CPK-08 and gel-type cation exchange resin Dowex 50WX8 were irradiated with γ-rays from ⁶⁰Co, while soaked in distilled water, 0.5 M HNO₃ or 4 M HNO₃, and the ion-exchange properties, such as strong- and weak-acid capacities, moisture content and wet resin volume, were examined in relation to absorbed dose. There was no appreciable difference between the radiation stabilities of the two cation exchangers. Increase of HNO₃ concentration reduced the loss of strong-acid capacity and increased the decross-linkage and the weak-acid capacity. Elution characteristics of ¹³⁷Cs and ⁹⁹Sr from columns packed with γ-irradiated resin were examined and the column distribution ratio of these radionuclides and the theoretical plate number were calculated. These values decreased with the increase of absorbed dose. Dianion CPK-08 was packed into a pressurized column and irradiated with γ-rays at a dose rate of 2x1O⁶ R/hr, while water was passed through the column at a constant flow rate. The greatest change in the resin properties was observed at an upper stream position from the position of the highest radiation dose of 2x10⁶ R/hr. (T.G.)