This study was conducted to investigate the effects of gamma irradiation on the change of volatile flavor compounds of raw oyster and its cooking drips using headspace methods. Major volatile flavor compounds of the raw oyster were identified as methylthiomethane and 1,5-hexadiene. When the raw oyster was irradiated at the dose of 5 kGy, 1-pentane was newly detected. On the other hand, 9 compounds including N-methoxyformaldehyde were identified as the major volatile compounds of cooking drips from oyster. Among them, N-methoxyformaldehyde contents in cooking drip was decreased by the gamma irradiation. By the gamma irradiation above 30 kGy, new heterocyclic compounds was found in oyster cooking drips. Therefore, the amount of volatile flavor compounds in the raw oyster and cooking drips were changed by gamma irradiation, and these results could be potentially used in the seasoning industry.