[en] DLC (Diamond-like carbon) thin film-deposited polycarbonate specimens were irradiated by high level gamma-ray and made observation of their irradiation effects. In order to do that, diamond-like carbon thin films were deposited on polycarbonate specimens by plasma-enhanced chemical vapor deposition, and then those specimens were irradiated in the high level irradiation facility in KAERI at the same dose rate of 10⁶ rad. Relative concentration of free radicals generated during irradiation of the DLC-deposited and undeposited specimens was determined by the analysis of EPR (electron paramagnetic resonance) spectrum at the elapsed time of 4 hours and 2 months after irradiation of those specimens. As a result of the analysis, it was found that the radical concentration in the DLC-undeposited specimen at the elapsed time of 2 months reduced rapidly in 4 % compared with that at the elapsed time of 4 hours, whereas the concentration in the DLC-deposited specimens decreased slowly in the vicinity of 60 %. Consequently, DLC thin film-deposited polycarbonate specimens resulted in the increase of radiation-oxidation resistance